Note: this is a guide based on what's currently known. As it hasn't been out that long (<2 weeks before this guide) there will undoubtably be updates and powercreep. To have access to this trial, you'll need to have cleared Bariura map and beat Trial 6: Afla Dilith. Ark is light element and the clear reward.

Recommended Teams:

At least one Grah 6* lead, and one other 30% or higher HP boosting and BB filling leader. Great combos: Grah/Bestie, Grah/Oguro, Grah/Grah, Grah/Ark (friend), Grah/Raga (requires atk down). Grah will need an elemental weakness sphere (Ideal: Secret Gem KarlEx, alt. Meruforna Bond4Warriors). If not just give him Secret/Buffer SeriaEx and guard him most of the time. For backup team 2, Cardes/Grah is a good choice (for stage 2, optional).

Damage boosting sub: spark damage is the ideal way so far to clear stage 1 with no items and no revives needed. Raga, Ruby and Claire are all really excellent for this trial. If you don't have a 7* spark buffer, I recommend Grah Ark (friend) leaders for Ark's 70% spark damage LS. Other good subs: Kira, Dion, Kurt, but they are riskier for part 1 and will do less damage. Kira would be preferred out of the last three, for his atk down.

InfiniteSBBer: Yura, Oguro, Taser. Yura=best, Oguro=Excellent, Taser=Great. Taser is less preferred than the others because Balgran tends to kill him. Otherwise he's great. Bring only 1 STBB. Nemeth Gear is also good. Yura will do the most damage though. Lugina is alright if you don't have them. You absolutely need STBB if you aren't bringing Raga/Ruby/Claire. Otherwise, optional. Alternatively, bring Balgran instead for better survival from his atk to def buff.

Mitigators: Elimo frontier. Hands down, best mitigator for this trial. Pair with Edea or Zel Deus to be able to use her UBB. Aaron is a good unit, but unfavorable element for this trial. Note if you are bringing Elimo and Edea, both must have status null spheres. (Suggested: Rafudonia FrontierGatelvl25 sphere on Edea) (Elimo=Drevas 10BC/turn).

BB Filler: Stage 2 has some strong BC drop resistance. Bring someone who fills BC when attacked: Medina, Diana, Kikuri or Bestie. Bestie=Best, Medina=Excellent instafill, Diana=Excellent, Kikuri=Good. Kikuri doesn't generally need elemental weakness null, as long as Grah is there, she's tanky enough (unless oracle). Kikuri and co are best with a secondary sphere of Magic Ore/EmpressTear/Vermillion (so you can refresh SBB buff every 3turns guaranteed. Alt: SeriaEx or LuginaEx sphere if you have enough BC. Don't have any of these? Bring friends, use Grah/Bestie or Grah/Oguro leaders. Bestie fills more BC than Oguro, but will do less ST damage.

Status Removal: Kanon, Ivris, Rinon, Veltrion. Rinon=best for this trial (good element, light/dark buff, healing on BB), Ivris=excellent (mostly for instafill in stage 2), Kanon (for def buff if no Elimo or Zel Deus), Veltrion (strongest heal, but no damage). Lots of all types status infliction by Ark and friends in stage 1. Of course, if you are bringing Elimo and/or Edea then you don't need them.

Atk Down (optional): only required for Grah/Raga teams. Rest don't need it. Ruby=best, Kira=great, Griel=OK.

Quick comment on bringing 6* other than Grah=you may be able to fit max two more 6* in party by giving them a mix of malice/buffer/secret LuginaEx/SeriaEx/KarlEx. But not if you're bringing dark units like Ivris or Kikuri, since you'll want to give them the stat boost from those Ex spheres first. It's risky though and 6* have weaker buffs/attacks in general.

Example team setups:

7* Spark Buffer: Grah Bestie (leaders), Raga/Ruby/Claire, Taser/Oguro/Yura, Elimo, Edea. (Or Balgran in place of infiniteSBB)

No 7* Spark Buffer: Grah Ark (friend), Bestie/Medina/Diana/Kikuri, Taser/Oguro/Yura, Elimo, Edea. (Or Balgran in place of infiniteSBB)

No Edea: Grah Bestie/Oguro (friend), Raga/Ruby/Claire, Ivris/Rinon/Kanon, Elimo, Zel Deus/Aaron

One Mitigator only w/ Spark Buffer: Grah Bestie (leaders), Raga/Ruby/Claire, StatusRemover/Healer, Yura/Oguro/Taser, Elimo/Edea/ZelDeus/Aaron. If bringing Elimo only (bring Keido), Edea (bring Selena/Will), Zel Deus/Aaron bring (Rinon/Ivris)

Grah Raga team: Ruby/Kira/Griel, Aaron/Elimo/Edea, Rinon/Ivris/Kanon, Medina/Bestie/Diana/Kikuri. Note: reliant on atk down to proc.

Optional Backup Team vs Ark part 2: Cardes Grah (leaders), Bestie/Medina/Diana/Kikuri, STBB, Mitigator, Healer/StatusRemoval.

Part 1: Ark and Friends

First two turns, Ark does some weak attacks. No mitigation needed until turn 3, where there is a small AoE. Use this chance to fill up your BB gauges, save your fujins. At 90%, 70% and 50% he will summon 2 of his friends each time. Dion/Yura must be killed below Ark 50% HP, Balgran/Medina below 30%, and Ruby/Rinon last. There's also a strong Ark AoE at 50% and ~30%. 140% Def buff is a must have for this part (Elimo, Zel Deus, Kanon). Or bring Balgran.

The best method imho, is to bring spark damage buff or LS, and use Elimo's UBB to protect your team for 3 turns while you wipe them all out. In this method, first use your STBB to whittle down Dion and Yura's HP. Then activate OD on Elimo, UBB and then wipe out Dion and Yura at the same time as bringing Ark below 50%. To do this: either bring another mitigator to keep up mitigation while Elimo's OD is activated, or put an angel idol on her and guard everyone else. (note: you cannot guard if paralyzed) Edea is the best 2nd mitigator. Zel Deus works too, but you will need another unit who can remove status. After UBB Elimo won't be able to remove status without overwriting her own 75% mitigation buff, so Edea or other must remove status before she UBBs. (Elimo UBB only prevents status, does NOT remove).

After you've wiped out Dion and Yura, focus on taking out Ark as quickly as possible. Then mop up Balgran. The rest are pretty weak. The spark damage and Elimo UBB is a great way to bring him down from slightly above 50% to below 30% in 3 turns to avoid both AoEs. Any other buff that can do the same amount of damage will work too, (ex. Kurt Keido) but might need second team against stage 2 Ark.

Alternatively, if you have Raga or Ruby but no Elimo plus a second mitigator, then you can activate Raga/Ruby's UBB right before Ark's 50% HP and wipe out them out as fast as possible. You may need a couple revives for this method.

If you are relying on Medina/Besti/Kikuri SBB to fill your BB gauges, try to have their SBB full when you kill the last of Ark's pals to be ready for part 2.

Part 2: Ark Stage

First up will be Ark 6*. Once you get him below 50% he transforms into 7* and heals back to full HP. (HP threshold below are all for 7* form)

Only gonna say this once, but It's important to never BB/SBB all your units on the same turn in Stage 2. 1 unit must normal attack or guard every turn or he will randomly remove buffs from and kill one random unit. Moving on...

The most critical part in the second half of this trial is the timing of the 3/6 turn STBB. The 3-turn STBB can be mitigated against, just be sure to guard Grah and any other dark units on that turn. Every 6-turn STBB OTOH removes all buffs from a single unit and must be guarded (guard all). Unfortunately, even with Cardes/Grah leads or Grah/Grah leads, Ark can still KO a unit even through guard if he focus fires on a unit. Worse, the real danger comes from getting hit with this skill after his 50% (as 7* usually at 30% or below) HP threshold, he activates his Overdrive and increased hit count, and his STBB debuff move doubles to twice every 6 turns. Basically it's a guaranteed KO for 2 units, even with guarding, double Grah leads and 16k unit HP. This is the most difficult part of the trial.

The good news is, if you've been repeatedly getting wiped at the 30% or the 10% mark, you can move the turn you get hit by the STBB. To do this: first play through normally and watch your damage each turn. Count turns starting from beginning of stage 2 (ark solo). Include all turns including the turn he transforms into 7*.

Note this timer does NOT reset. I suspect there is some confusion about this point, because if you reach any HP threshold: 50%, 40% or 10% then that HP threshold attack takes priority and the STBB is skipped. It does looks like it has reset. The name of the move even changes after 50% but they share the same timer. If you time it so turn 5 is a threshold attack, but the next isn't, you will indeed get hit by it on turn 6.

Now, right after he transforms, he puts up mitigation and you won't really do much damage anyway. If you normally attack during this turn, then on your second run, don't. Just guard. Or renew some buffs and mitigate. Doesn't matter. The important thing is to watch your damage, and try to get turn 6 to fall at either the 50% or 40% threshold.

In addition to the 3/6 Turn STBB move, he will randomly activate a damage reflection buff, "Revenge Shift". He can do this randomly any turn after he transforms. To check if Revenge Shift is active, just check his buffs, the icon looks like a person with a ray bouncing off it. On these turns don't attack, just guard all and you won't get hit by it. Note any pure support or heal BB/SBB are fine to use on these turns, just don't attack. (note: Ivris's BB does damage).

Going into the <50% threshold, you don't need mitigation up, just be prepared to heal next turn. You will be left with 1HP or more on all units no matter what you do. Just Heal, Guard All if HP not full, and mitigate if you won't reach <40% next turn. If you will, don't mitigate. Not mitigating will save your BB and a fujin for the <40% threshold "test". (Of course, if you have a lot of BC generation then this doesn't matter.)

At <40%, Ark will demand you show your determination. All your units must BB or SBB, even if they are non-damaging BBs/SBBs, or Ark will remove all buffs and KO your entire team. Of note, if you only have 5 surviving units, but BB/SBB all 5 of them, this is acceptable to him. Use your fujins if you don't have BB ready. (I've heard you can survive this with Cardes/Grah leads and guard all, but I have not tested this, try at your own risk)

If you got the 6-turn STBB to fall on the 40% or 50% mark, then great! You now have 4-5 more turns to kill him without getting hit by it. There is a moderate AoE around 30% and a powerful wipe at 10%. 10% wipe does not debuff, so angel idols and UBB mitigation will work here. You have several choices:

1. Use Raga or Ruby UBB at slightly before 50% threshold or <40%. You can nuke him with Raga or Ruby subs and dark element buff in three turns or less from ~30%, completely skipping the 10% AoE altogether. From above 50% needs additional Yura/Oguro/Taser subs.

2. Use Yura, Oguro or Taser SBB, plus dark element buff and increased spark damage LS/buff to kill him. (don't need UBB for this) Again, you can skip the 10% AoE this way. Yura's DoT in particular is very potent against Ark.

3. Let the <30% AoE wipe out your first team. Save at least 1 fujin for team 2. Fill second team with Maxwell/Kira lead, and some combination of dark damage boosters/attackers such as: Kuda, Mifune, Zergal, SGX, Elza, Afla Dilith, Feeva, Kikuri etc etc. Put friend as Tilith. Fujin Tilith, BB/SBB everyone and nuke that last tiny bit of Ark's HP left. I'm not sure if this works from 30% HP, but definitely does from 12% (and, if you have your own Tilith you can do Maxwell/Kira or Kira/Kira leaders. But I think most don't have her.)

4. Tank the damage with Elimo's UBB. Use a Hero Crystal to refill UBB, then nuke Ark with Will, Loch or other nuker UBB while Elimo's is active. I don't really recommend this option. Mostly because Hero Crystal takes valuable item spot that could be more fujins or angel idols. And you'll want backup fujins for either 40% threshold or for your second team. It's very risky.

5. If you have Loch, and are good at sparking his UBB he can also kill Ark from slightly above 10%. Higher if you brought spark damage buff/LS. I recommend practicing the spark on a raid boss or something, there is a slight delay that makes the timing a little tricky.

Note that the damage reflection buff can still activate randomly after 30%, so watch out for it.

Remember: count the turns, watch out for damage reflection, and keep an eye on your HP thresholds. And always normal attack or guard 1 unit every round in part 2. Good Luck!

Ark LS, BB/SBB info