The first of our Valentines Omnis in 2017, Fei and Fang have skipped an evolution to try to find a way into the meta. They're bringing a relatively unique feature to the playing field which looks like it may secure them a place in FH runs for the foreseeable future. Though I personally feel their overall kit is lacking a significant amount of important buffs at a glance, the damage against full enemy groups will be impressive and their LS may help them find a place outside of FH as well.

There's a lot of general mechanic discussions in here at various points since I decided to clarify drop rate mechanics fo rthe sake of the LS BC counter, so the analysis is going to look very wall-of-texty. Well, mine usually do, but... more so.

The pair's announcement and initial reddit discussion can be found here: https://www.reddit.com/r/bravefrontier/comments/5srrf4/fei_and_fang_omni_evolution_unit_details/

^{I wanted to call them Feng for short, but we already know we're getting a real Feng by the end of next week. And she's cute.}

Stats/Arena/Animation

• Fei and Fang bring an all-rounder stat set to the table. While it has no particular weaknesses, it has no particular strengths either, and given they may perform best in a nuking slot, it's a little disappointing to see merely average ATK on the pair. Means that much more effort to approach the ATK cap.
• In the arena, they don't really have any special abilities other than elemental immunity. Ther BB should hit like a truck and is multi-elemental, which is nice too. Really the only major positive here is they're not weak to popular fire units such as Azurai, Glenn and Rahotep
  • I personally find it odd that their BB and SBB are double attacks to show off the nature of their being two of them, but they get absolutely no hit count related stuff? Like, their basic attack should have 1 hit count from ES by default to mirror the BB skills or something.
• Their animation data isn't available yet. What we know for sure right now is that they have a regular movement type (very likely speed 3 as with their previous evolutions) and between their two AoE they spark a single hit on SBB automatically (gauranteeing two spark's worth of spark heal/BC in any situation, though I'm sure players will aim for more). They should be perfect sparkable with dupes and likely go in the same slot as Rize or Lasswell in FH squad building.
  • I'll be coming back to talk about this as soon as I notice the datamine updating to include the pair.

Passive Skills

LS

• The two have a spark/BC-oriented LS which grants 40% all stats (50% enhancement available), 100% spark damage, 30% BC/HC drop rate, 50% BC/HC drop rate on spark and after a unit collects a rolling total of 60 BC, grants that unit 2 turns of 20% mitigation.
  • While not a top tier damage LS, the spark damage here is still relatively significant. You don't lose too much taking them as a leader for the utility.
  • The two provide a huge amount of BC/HC drop rate. Very few LS provide more than 20% normally, and the spark BC/HC here is extremely high as well. High HC drop rates are especially notable as HC drop rate has a very low base compared to the values Fei/Fang will let you reach. This is going to have to lead into a discussion on how resistances work as it's important to the mitigation/ES/SP buffs later on as well.
    • Firstly, resistance is separate for each of the drop types, and is split between Base drop resistance and Buffed drop resistance. An enemy can have any combination of values for the four resistance stats this creates. The differences between the stats allow for situations where enemies might have regular drop rates normally but react poorly to buffs, or have terrible base rates but still offer signfiiant gains for using buffs.
    • The Base resistance stats apply to the basic drop values for each type. This means they apply against 35% for BC drop rate, and 10% for HC drop rate. Base resistance is easily translated to actual redcution as a result - 10% base resistance against BC is a 3.5% reduction (31.5%), and 10% base resistance against HC is a 1% reduction (9%).
    • The Buffed resistance stats apply against the sum total of all bonuses, ignoring the base value. An enemy with 50% Buffed BC resistance would halve the value of every single BC/HC drop rate effect on that unit - for example, Fei/Fang's LS values would be reduced to 15% 25% on spark.
    • The final drop chance is the modifed base drop rate added to the modified buff drop rate. Just using the above example numbers you'd hit 46.5% BC drop (61.5% on spark) and 24% HC drop (49% on spark).
    • Some more notes:
      • Drop chance caps out at 100% (which is reachable). The cap is applied after resistance, so you can still hit 100% drop chance against any enemy which isn't totally buff immune with strong enough buffs.
      • Drop chance is doubled if the target being hit is already dead (this also applies to item drops, by the way - depending on the enemies a nuke squad may do as well in item farming as a Zeruiah/Zelnite lead squad)
      • For BC drops, each attack has a drop check modifier which applies to each individual hit and controls how many times the attack will roll for BC drops. This value is typically 1 for most AoE BB attacks, but normal attacks, single target BB skills and extremely low hit count AoE will often have more than one drop check per hit, allowing for higher total BC drops. Thankfully Gumi have since last year included drop check data in unit announcements, though JP players still need to check datamine threads on reddit or other forums such as appinvasion for JP's releases.
      • For HC drops, there is only one drop chance per hit, so the max HC drops for any attack is simply (amount of targets hit) x (amount of hits in the attack).
• The final effect of the LS is the mitigation buff. This effect keeps track of the BC drops each unit has received and grants that unit a 2 turn mitigation buff whenever the total reaches 60. Some notes here:
  • This kind of mitigation buff is additive with mitigation from pure passive sources and BB/SBB-tier non-elemental mitigation buffs. As with those effects it's still multiplicative with most other mitigation sources.
  • When the total hits 60, the counter resets at end of turn. No further BC carry over to the next turn.
  • The mitigation buff lasts for 2 turns starting the turn it's triggered, so you need to average 30 BC per unit per turn to maintain it.
  • The counter only checks physical BC - BB fill from other sources don't mean anything to it, and the value of BC modified by BB fill rate buffs and debuffs doesn't matter either. BC specifically refers to the BC crystal itself.
    • The important thing to note here is that even if an enemy somehow reduces your BB fill rate to 0%, you can still trigger this LS as long as the enemy is not immune to actual BC drops. On the other hand, an enemy that's totally immune to BC drops will never let this LS trigger even if you can fill consistently through spark BC.
  • The mitigation buff will not stack with similar effects from other leaders, spheres, extra skills or SP enhancements. While in most cases this is not harmful (and in fact the likely mix of triggers makes it more likely you'll have the buff up at any given time), a particular note goes to Fei/Fang's own ES which has a 25% mitigation buff triggered by HC drops and can overwrite or be overwritten by the BC threshold mitigation from their leader skill.
    • Using multiples of the same trigger (i.e. using two Fei/Fang leaders) is redundant however, as they would always trigger at the same time and only one buff stays.
• Overall this LS provides a very strong combination of damage, BC support, healing and survivability and feels viable if you can pull off the requirement consistently. That said, optimal usage of these units as nukers may involve BB ATK focused LS as they will not naturally come close to the ATK cap.
• Fei and Fang lost an effect here - one which would have had an interaction with the mitigation, but... oh well. They lost their damage reflect chance, and damage reflect can produce very small amounts of BC/HC. To be honest, triggering the mitigation buff at the end of an opponent's turn this way would actually be harmful because it would effectively cut a turn off the duration, so it's not a bad thing they lost damage reflect.

ES

• Fei/Fang have a fairly complex ES. It has three effects - elemental immunity, 100% spark damage for 2 turns after picking up 30 BC and 25% mitigation for 2 turns after picking up 20 HC.
  • Elemental immunity means they don't take more damage from Fire units. Pretty simple, and a nice bonus to general squadbuilding viability as you don't have to worry about it for these two. I actually like this design choice - Fei and Fang are realistically both an Earth unit and a Water unit, so their weaknesses cancel out. Shame their resistances don't add together instead though, but that'd be a pain to code effectively using abilties in the game without making them effectively more resistant to fire than thunder.
  • The spark damage buff here stacks with BB/UBB tier spark buffs and all pure passive effects. However, for the few LS which provide a similar trigger = spark buff effect (e.g. Zero), the buff will not stack with the buff from those LS. As the ES isn't optional it could be a slight bit problematic, though few of the threshold spark buff LS are in particular usage right now. It's also a little sad there's no way to trigger this in OTKO scenarios as the buff can't trigger until all attacks are finished.
    • Note that unless Gumi have done a smart and made the buff 3 turns in data (can't check at time of writing), the first turn of the buff will already be over before you get a chance to attack with the unit again - because BC drops are always collected at the end of your turn, and buffs triggered on your turn will have one turn reduced from their duration at the start of the next one, leaving this spark buff with only one turn you can make use of it in.
      • So it needs 30 BC average per turn to maintain... same as the mitigation buff.
    • The BC requirement here follows the same rules discussed with the LS mitigation buff.
  • The mitigation buff is similar to the one described before, just with a higher value and dependent on HC rather than BC. As I mentioned, however, it doesn't stack with other trigger = mitigation buff abilities and has a higher value than most of them. For this source in particular, it's likely to be negated by most damage taken = mitigation leader skills such as Ark or Rain.
    • Makes it an odd one, really - generally you'd want that kind of ability for every unit in the squad, but taking a leader skill that makes that happen easily also threatens to negate the value of this passive entirely.

BB Skills

BB

• Fei/Fang bring a unique feature to the table here - their BB is a double attack where both attacks are AoE and there is no special condition on the second AoE. This feature is also present on their SBB. The BB is also earth/water dual element (on the main AoE only) and grants 130% spark damage, 35% BC/HC drop rate ( 10% enhancement available) and 400-500 HP spark heals for 3 turns.
  • Double attacks calculate damage for each attack individually, which means all ATK-based damage buffs will be doubled, as well as the ATK cap (it's calculated individually for the attacks, though they should hit the ATK cap around similar ATK% values). The individual attacks will also roll RNG separately, which means crit will tend more towards the expected average. This also adds one infliction chance for any infliction buffs you might have given the pair.
    • The second attack here isn't dual element, which means without an element buff Fei/Fang are going to perform a little weirdly against fire units, dealing super effective damage on the main AoE and resisted damage on the second AoE. Chances are you'll have element buffs anwyays, but this feels somewhat interesting to me.
  • In a large AoE scenario, the double attack gives Fei/Fang the highest overall damage output capability in the game. In FH where you expect to see up to 6 enemies, all of different elements, Fei/Fang will deal their damage 12 times while other units will deal a max of 7 attacks - giving Fei/Fang a 71.4% higher damage cap against 6 targets than, say, Lasswell. While some of that advantage will be lost in Fei/Fang not inherently reaching the damage cap on their base AoE and having 100% less spark damage and 70% less crit damage, especially when using something like Avant's UBB and LS to shrink the gap in per-attack damage I fully expect dupe-sparked Fei/Fang to outperform dupe-sparked Lasswell for FH score purposes.
    • This damage advantage does fall off or disappear entirely against smaller enemy groups and we may need to do some testing to define how many targets there need to be for the pair to outdamage Lasswell.
  • Spark damage is usually good damage. Fei/Fang don't get an enhancement to this, so using them for FH nuking is likely to force you to be unable to use a top tier 150-160% spark damage buff, but hopefully the value of the two as a nuker surpasses that. In most other content damage isn't so critical is to make this a major loss, and it should be considered against the rest of their utility as a unit.
  • The BC/HC drop rate just adds to the ridiculous amount already given by their LS - between LS and BB alone the pair will take a squad to 100% BC drop rate against enemies with no resistance, as well as 75% HC drop rate (100% on spark). Obviously in most late-game content the drop rate is reduced heavily and 100% is less likely to happen, but packing that much should still go a long way towards supporting BB spam. By itself the BC buff is relatively minor in the current state of the game, but HC drop rate is still fairly solid paired with REC buffs and high hit count units.
  • Finally, spark heals. They're... something. These heal for the RNG listed amount on spark (I believe with a very small REC bonus as I've seen numbers out of the RNG range when using Zero), meaning a unit's healing capability through spark heals is mostly limited by its hit count and sparkability. Generally speaking I feel most squads manage enough healing through a burst healer paired with a REC buff, but in the event you still need more spark heals are solid if you spark consistently. Overall a pretty minor buff that's nice to have but doesn't define a unit's role.

SBB

• A slightly more powerful double AoE which still provides a spark buff, but swaps the rest out for a 100% tri stat self buff ( 30% enhancement available) and 10 BC insta-fill.
  • The double attack and spark buff are more or less the same as before. Obviously the SBB is almost certainly going to have slightly higher damage modifiers, although Gumi didn't give us values for either BB or SBB damage.
  • The tri-stat buff is a self-buff, meaning a) it doesn't apply to any other unit in the squad and b) it stacks with regular and element-specific stat buffs. This offers Fei/Fang a good personal damage increase which they benefit from more than usual due to the double attack, well, doubling the effect of ATK% on their BB/SBB damage - moreso than Lasswell benefits from his water ATK buff as Fei/Fang need the extra help to cap damage on both of their AoEs.
    • As it's stat buffs, it can be converted. You can pump their ATK higher using a DEF->ATK convert, and the ever popular ATK->DEF conversions will work well here too.
  • BC insta-fill is a nice effect which tops up the other units in your squad when it triggers. This may prove to be exceptionally useful for FH squads if you run dual Fei/Fang, as that's 20 BC per turn to every other unit in the squad and 10 BC per turn to the Fei/Fang pair. In other content, BC insta-fill is always nice for ensuring you can top up a mitigator that failed to fill, although it's less useful in this case as it's only available on Fei/Fang's SBB and therefore unavailable if they get BB drained below that threshold.
    • Important to note that BC insta-fill doesn't affect the unit causing it. Assuming Fei/Fang have regular timings, the fill should occur when they begin attacking after traveling across the arena, so with global's current auto battle you should expect the fill to occur after all units have begun their animations unless you intentionally add a high delay.
  • While I rarely bring up BC costs, I'd just like to note that at 48 BC total, Fei/Fang's SBB is actually relatively cheap (compare: Azurai at 68, Lasswell at 56) and they should be easy to fill consistently off spark BC on a single target with their 29 hits as long as you have a good spark setup for them (2 hits autospark regardless). This helps make up for them not filling themselves with the insta-fill.

UBB

• A nuke which is unfortunately not also a double attack. Fei/Fang work together to grant the entire squad elemental and crit immunity, while also increasing spark damage by 300% and BC/HC drop rate and BC fill rate by 100% for 3 turns.
  • Generally speaking, people try to slot squads for crit/element immunity at the LS or BB/SBB level if they're really necessary, so it feels like a fluff effect on a UBB that doesn't really define it. It'd be nice if the UBB version of these buffs was given special attention by Alim (like being immune to buff wipes) but at present I don't believe that's the case.
  • The spark damage is pretty big, but by itself doesn't make this a strong enough nuking UBB to be considered for that purpose. For that single damage buff to be worth using it'd have to be paired with something highly valuable like mitigation, but well... it isn't.
  • BC/HC drop rate is what it is. This is very likely to push your BC/HC drops to stable levels even through resistance, but there are UBB out there which just plain fill the HP/BB gauges withotu going through something like this. It'd be good for triggering Fei/Fang's LS mitigation, but why would you choose that over using UBB mitigation?
    • Note that no matter how much BC/HC drop rate you add through buffs, the real drop rate doesn't go above 100%. You can't get multipe BC/HC drops from a single RNG roll.
  • The BC fill rate feels like an afterthought buff. Sure, it goes well with BC drop rate and most units will be able to fill consistently, but this is not the only UBB that enables that and most other BC filling UBB have good value elsewhere as well. It's important to stress again here that increasing the value of each BC does not increase the amount that drop for the BC counters present in Fei/Fang's LS, ES and SP.
• Ultimately I feel this thing lacks value in any general field you look at it from. Two of its buffs are present on BB and SBB at the same value, the damage is subpar compared to nuke UBB and the BB/HP support is subject to resistance when there are UBB that offer more consistent BB/HP gauge fills which are affected by less resistances overall (BC drop is affected by fill rate debuffs and BC resistance vs BB regen only being affected by fill rate debuffs, and there aren't any healing debuffs that affect full regen).

SP Enhancements

As with all OE units, Fei/Fang have a bunch of SP enhancements that you're supposed to put a build together with. Though it feels like they're missing something here as you'll have lots of leftover points in a pure nuke build.

• 20 SP: 20% All Stats
  • Generic stat boost build filler
  • It'll be included in the nuke build as there's not much else to buy for it. It should also be seriously considered for content bulds as again there's not much to choose from.
• 10 SP: 70% Spark Damage
  • Nuke build fluff.
• 10 SP: 70%-> 100% Spark Damage
  • More nuking
  • The core of a nuke build with these two. No other enhancement series raises their damage even close to as much.
  • The SP cost for 100% spark damage for this pair is only 20 SP. Compared to other units that's fairly cheap, but the saved cost doesn't let you take any other large damage pumps.
• 10 SP: LS 10% All Stats
  • Cheap stat buff. Fairly important for Fei/Fang's LS as using the LS for defensive purposes when it's got signfiicantly lower stat bonuses than other mitigation LS leaves it at a weaker value.
  • Nuke builds can fit this in too, in the off chance you want to use your nuke Fei/Fang somewhere else as leader.
• 30 SP: 50% boost to Atk when BC collected has exceeded certain amount [30BC]
  • An ATK boost that follows the same counter as Fei/Fang's LS and ES.
  • Because it can only proc at end of turn, this doesn't add much to a nuke build and instead has slightly more viability in slower content where you can convert the ATK to DEF. That said, the cost is a little restrictive when there are more readily available stat boosts to consider as well as strengthening the squad-wide effects of the unit.
  • The damage boost is relatively minor for the SP cost and I wouldn't bother with it personally.
• 30 SP: 50% boost to Def when HC collected has exceeded certain amount [20HC]
  • More or less the same thing as the previous one, but has more defensive merit due to boosting DEF directly.
  • Still hard to justify compared to the other things hard-content-Fei/Fang are going to want.
• 30 SP: Adds status ailment negation for 3 turns effect to BB/SBB
  • The start of something that turns Fei/Fang into an unexpected null/cleanse unit.
  • If taken with cleanse, becomes very useful for end-game content. Negation by itself can work in some situations, but if enemies have buffwipe/infliction pairings or stat debuffs, you'll definitely want cleanse as well.
  • As with all buff addition effects, consider whether you'll be using other units with the effect already in their kit. I feel null/cleanse are commonly found on units with staple defensive buffs and therefore not difficult to slot, which may mean it's not important on Fei/Fang.
    • Though certainly the option is interesting.
• 10 SP: Adds status ailment removal effect to SBB
  • The other half of the null/cleanse pair. Actually pretty damned cheap at 40 SP total.
  • Cleanse is not added to the BB, so you have to be careful with it. As long as you're not getting buff wiped every turn yo'll still have plenty of chances to set up Fei/Fang's BB buffs if you want, but you'll want to be able to SBB on demand if you somehow suffer a buffwipe ailment on the same turn or DEF debuffs are common.
  • Also note that Fei/Fang have no inherent immunity to ailments, so you'll need to provide that for them via sphere or elgif to be safe. Preferably elgif as no current content causes ES null except summoner's arc (where you won't be using OE units with SP enhancements active for a long while yet and for all we know OE units will unlock ES before SP enhancements there anyways), though sphere null is also very rare outside of the arena.
• 20 SP: Enhances BB's BC and HC drop rate [ 10%] effect
  • Makes the buff worth 45% BC/HC drop rate, which is toppest tier for BC/HC drop rate at the moment. Every little helps.
  • It's relatively cheap, but unfortunately the buff is only on BB and therefore not valuable for FH nuke builds.
• 30 SP: Enhances SBB's Atk, Def, Rec [ 30%] self-boost effect
  • 30 SP for 30% ATK/DEF/REC which can be buff wiped. It does stack with stuff though.
  • Well, for the nuke build you don't have any other options which compete, though it's small enough you might consider bypassing it just to give them more useful abilities for other content. For content builds, increasing squad utility is more important than a relatively small stat boost.
  • If you're just looking for defensive bonuses, this is better than the BC->ATK and HC->DEF options with a good ATK->DEF conversion. 70% ATK->DEF gives 21% ATK->DEF and 30% DEF from this SP enhancement, and Fei/Fang will have a naturally higher ATK than DEF in any typing making this worth more DEF than 50% DEF or 50% ATK alone.

SP Builds

There's basically just 2 builds here.

The optional choices differ per build.

The Nuke build gets to choose between one of the 30 SP stat bonuses that will never trigger on turn 1, or the BC/HC drop buff that's on BB and will never be used plus the LS that is unlikely to be used in FH. It's not a stellar list of options, but the latter pair offers more viability outside FH. I guess you could also have null without cleanse or cleanse without null here if you really wanted...

The Content build gets more options - it can take some combination of the LS enhancement, the 100% spark damage option and the BC drop rate option (pick two), or it can take the tri-stat enhance or one of the 50% stat buffs I suggested not taking before the tri-stat enhance.

At any rate, Fei/Fang's builds end up relatively homogenous, with having/not having the ailment cleanse/null being the major build definer. They could really do with having at least one more effect that could properly define a build or at least force a choice for the player beyond "do I want to use another unit for cleansing?".

And honestly it's that lack of meaningful options that'll probably make me just gear mine for nuking and use other spark buffers and cleansers in other content. Fei/Fang don't provide enough significant buffs for my liking on top of having their utility split between BB and SBB despite only having 4 squad-wide effects on their base BB/SBB kit.

That said, I do recognise that having more unique options for cleanse/null will help players in squad building, it's just there's almost never clash between spark buffers and cleanse/null units in the first place.

I also feel that while the LS has strong potential, it suffers from enemy resistances, is dependent more on RNG than Rain or Ark would be, and offers less general survivability than either of them due to the lower stats. Very few players should still be struggling to field Ark in some form either using their own or a friend's, and many players at least have friend Rains as well as he's still a popular leader, so there's little reason to pick Fei/Fang as a leader right now unless you need a second for dupe sparking in which case the LS isn't even your main concern.

But plus side, new high value nuker, and it's a permanently available unit. Though... the stress of making the necklace to evolve them will be particularly high once the valentine's event is past us (assuming the drop rates in the event-specific dungeon are high enough to make it bearable when that starts - if it's not evolving the two could be stressful even during the event).