Warrior

War Maiden

Leader: Boosts allies' ULT Damage by 80%, Boosts EXP received from battle by 50%.
ULT: Light attack to single enemiy.
Talent: Gradually recovers HP in battle

One of the most powerful units in the game, alongside Last. Her leader skill just screams OP in your face, rendering our friends Ron and Sean(4star) completely useless as leaders. Her ULT is ideal for wiping out dark enemies (It was super effective!) but not only that, she can probably melt down any other element as well with her beastly stats. And her talent, recovering HP by herself, makes her even harder to kill. God-Tier unit hands down (literally). Now imagine Her leader skill paired with Last's. Shivers

LoliLilo.I

Leader: Boosts allies' ATT by 15%, reduces incoming damage by 15%.
ULT: Medium fire attack to all enemies.
Talent: Absorbs 20% of her damage dealt as HP.

Probably the best unit you can get for free, but that's disputable because you need to complete a lot of collections just to get enough Lilo.I's to evolve her to 5 stars. First off, her leader skill. It's good, since its boosts are not element restricted. 15% damage boost is not amazing, but the 15% damage reduction is quite useful. If you have a squad with mixed elements, she's the one to use. Her ULT is very powerful. As I mentioned earlier, she's a must have for those F2P players, or even P2P players if you need that extra damage. Her talent is pretty nice, considering it works with her ULT, recovering her to full HP after raining scarlet swords down on your helpless enemies.

Fina

Leader: Reduces damage dealt by enemy light units by 25%.
ULT: Great light damage to single enemiy, and reduces their ATT by 20% for 2 turns.
Talent: Becomes immune to Paralysis, Petrify, Poison and Curse.

Her leader skill is not good at all, since it guards against only a single element. It does have its situational uses, so not necessarily trash-tier either. Now look at the ULT. It has something other than damage! That just automatically grants it a high place in the tier list. Her talent is incredibly good too, making her immune to most status ailments which are a pain to deal with a lot of the time.

Seth

Leader: Boosts attack of Dark heroes by 50%.
ULT: Dark attack to all enemies, and reduces their REC by 50% for 3 turns.
Talent: His damage increases the further he is from the enemy.

Need a leader for your mono-dark team? Seth is your man! 50% boost to attack is absolutely great, no doubt about it. It's drawback is that not everyone can afford to have a mono-element deck, if you have a Seth, keep him until you've summoned enough dark units for a mono-dark squad, then proceed to stampede over your enemies. The REC down on his ULT.. Eh, I'm not too sold on it. I mean, is the enemy really going to be healing huge amounts? After playing for a while, I found that some bosses heal for a ton making them unkillable. Seth might be of assistance here. But still, has good damage as well as a nice hit count so it's nice for comboing. His talent seems to be one that give him a damage boost if he's in the back row. pft, some warrior you are XD

Riya

Leader: Boosts water heroes' attack by 50%.
ULT: Massive water attack to single enemy.
Talent: Deals 50% more damage to Dark enemies.

So why is a nun water type, you ask? Well she deals weak element-equivalent damage to dark types, so let's settle with that. Her leader skill is great for a mono-water squad. Her talent is what makes her interesting. you can stick her in a light squad, because she deals the same bonus damage as a light hero would deal, at the same time not suffering from the mutual weakness of light and dark types. This will actually help the survivability of your light squad significantly. Additionally, you could just use her in a water squad to counter not one but two elements. Good unit with diverse uses.

Dawn

Leader: Boosts earth heroes' attack by 50%.
ULT: Earth attack to all enemies.
Talent: Boosts critical damage of normal attacks by 100%

Essential earth squad leader with her 50% attack boost. Although it is nice to have a 100% boost using another 50% friend, that would make her talent go to waste, so try pairing her with a crit booster like Spring. Using her with spring will triple(?) Dawn's normal attack damage, providing it crits. If you're aiming for an earth team or just happen to have a lot of earth heroes, consider crystal trading/buying her fragments and raising her up.

Mitz

Leader: Boosts all warriors' ATT and DEF by 30%.
ULT: Dark damage to single enemy.
Talent: The next attack after using her ULT has a 100% crit chance.

HUGE leader skill, boosting 30% ATT and DEF regardless of element. Too bad it only works on warriors, so you'd have to use a lot of warriors to make good use of it. Her ULT uses clones and stuff, nothing too special. Her talent can make her incredibly strong. Getting a damage boost right after using her high damage ULT is a pretty good damage boost. Furthermore, using her with a Last leader will boost her ULT sustain and you can even use her ULT on consecutive turns, making them crit for huge damage.

Wizard

Last

Leader: Recovers 50% fury gauge after using ULT.
ULT: Dark damage to all enemies.
Talent: If HP is below 50%, heal for 35% of his damage dealt.

One of the strongest leader skills in the game, he's up there with War Maiden. As mentioned earlier, pair this dude with War Maiden and you'll have a deadly combination. He also has a self-sustain just like War Maiden which is nice. His real value, however, is in his leader skill. It'll allow you to dish out a LOT more damage, not to mention better fury sustain for your healers. Yes, having two Last leaders will grant you unlimited ULT.

Roy

Leader: Boosts attack of Thunder heroes by 50%.
ULT: Thunder damage to all enemies.
Talent: Huge boost to critical hit change when HP is full.

The highest tier wizard out there. His leader is superb for a thunder squad, it has the same perks and drawbacks as Seth which I mentioned earlier so I shall skip the explanation regarding that. His ULT is plain thunder damage, nothing much to see there. His Talent in interesting, it requires him to be at full HP to get a huge potential damage boost. This means you'd have to have 1, ideally 2 healers at the ready to maintain his full health. Great synergy with Linda and Ling.

Anna

Leader: Boosts attack of Fire heroes by 50%.
ULT: Fire damage to all enemies.
Talent: Recovers some HP when taking damage from fire-types.

Another 50% booster! Just goes to show that damage is something that is really valued in this game. Her ULT is once again plain damage. Now let's talk about her talent. It's reminiscent of a certain pokemon skill... Anyway, it's great for the arena. Why, you ask? Most players are going to have a Lilo.I in their arena team for damage dealing, and this sexy girl here is going to counter that with her superior boobs. One of the best fire/wizard to have.

Uygur

Leader: Boosts attack of Fire and Water heroes by 40%.
ULT: Water damage to single enemy.
Talent: 5% damage increase after taking damage from a water or fire enemy. lasts for 3 turns.

Only the chosen ones can be blessed with a good mono squad. Don't worry! here's the solution to all your problems! His Leader Skill boosts damage for not one, but TWO elements! It's a loss of 10% compared to the mono-element counterparts, but give your team-building a HUGE increase in flexibility. It also reduces the chance of getting absolutely screwed when faced with an element with you're weak against. His Leader skill is basically his selling point, the 5% boost from his talent isn't even worth talking about.

Shin

Leader: Reduces critical damage taken by 75%
ULT: Water attack to all enemies
Talent: When HP is above 50%, boost damage by 20%. When HP is under 50%, heal for 20% of damage received.

A story character who pretty much disappears after the prologue. His leader skill is decent for a arena defense squad since there will be people who run crit teams. But if you meet a normal high-damage team, consider yourself screwed. In short it's unreliable so just don't use him as a leader. His talent is also interesting, 20% damage increase isn't something to overlook, he should find his place in a damage-focused squad.

Assassin

Lia

Leader: Boosts Female heroes' ATT and DEF by 30%.
ULT: Massive thunder damage to a single enemy.
Talent: Reduces the enemie's DEF by 15% if she attacks from the back line.

Uhh... Waifu squad leader...? Exclusive leader skills like these are just situationally good. She'd probably go well with a Ling friend with a bunch of other female nukers like Flame Maiden. Even with yet another weird Talent, her ULT has good damage despite being a single target attack, if it says so in the description, it must be pretty strong. Her leader skill is top tier. Her damage is also top-tier, but in exchange, she has low DEF. A glass-cannon single target nuker.

Mika

Leader: Boosts Allies' critical hit damage by 100%.
ULT: Dark attack to all enemies .
Talent: Gives 20% bonus Critical chance to next attack.

His attack animation is LONG. Endless hits, he was just born for comboing. His leader skill give a massive critical damage boost. Not too good without any reliable sources of crit chance, and if paired with some crit chance, he would probably provide one of the highest damage potentials in the game. He would go well with crit chance leaders like Spring or Flame Maiden.

Flame Goddess

Leader: Boosts allies' critical rate by 35%
ULT: Great fire damage to single enemy.
Talent: Boosts ULT damage by 50%, but increases fury cost by 15%.

A nuker at first glance. She's the only fire unit with that crit chance leader skill, so points for uniqueness. Her ULT is single target. It deals massive damage, though, which I think makes up for it, especially if you're facing a boss or something. The cost might be hard to manage, so try use her together with Last/Linda/Ash.

Ash

Leader: Recovers 20% HP when landing a crit, and if it's the first crit, recovers 60 fury.
ULT: Massive earth attack to single enemy, chance to poison
Talent: Makes his sub-equipment equal in power to his main one.

Abysmal DEF. Use a shield instead of dual swords, god dammit! yeah, he's basically the earth version of Lia, both being glass cannons. His Leader skill works once per stage, which basically gives a full fury recovery as well as decent healing. Another hero with good crit synergy. His ULT is again, like Lia's, a single-target nuke. Good for tough enemies. Not sure if the poison would be too useful though, since it has a low chance.

Spring

Leader: Boosts Allies' Critical chance by 35%
ULT: Massive earth attack to single enemy.
Talent: Increases her critical chance and damage by 60% on her first attack.

She has a nice and fast attack animation, good for auto-battle. As for her leader skill, pair her with heroes that have critical-related effects like Ash or Mika. Her 60% damage boost is no joke, and made even better with a bonus 60% to her critical hit chance. I wonder if this game has a critical chance cap? If your ULT crits on the first turn paired with Mika, put your safety goggles on.

Dori

Leader: Boosts all allies' attack by 30%
ULT: Attack on single enemy.
Talent: If she's in a party with any other Elder, she gains 15% bonus attack.

30% attack boost regardless of element is fantastic if you can't afford a mono-element squad. Even though Mitz's one provides 30% ATT and DEF, that only applies to frontline warriors so I say Dori beats Mitz in terms of leader skill. Her ULT animation is terrible(apparently). Her talent activates if an Elder is in the squad. The Elders mean one of the 12 Elders in the story, which include Last, Mitz, and Dori. The other Elders are currently unavailable.

Archer

Ling

Leader: Gives a 60% boost to attack of all allies with full HP.
ULT: Massive Thunder damage to a single enemy.
Talent: Decreases crit chance by 4%, boosts attack by 10%

A fantastic leader skill with a huge drawback to make up for its power. If you're planning to use her as a leader, you better have 1 or 2 healers on your team with the rest being nukers. She obviously isn't suited for difficult battles, use her to power through relatively easy quests. Her ULT is a powerful single target nuke. As mentioned earlier, Roy's talent can make great use of this leader skill to boost his damage even further, and with his AoE attack, he'll probably end up compensating for Ling's lack of damage. Her talent is another 'sacrificial' type, 4% crit chance isn't too much to worry about.

Gen

Leader: Marks an enemy at the start of every stage and reduces their DEF by 80%, and reduces their damage dealt by 10%
ULT: Earth attack to all enemies
Talent: 6% attack boost for every earth or female unit in team

Her Leader skill. wow. 80% is a massive reduction! She should be an assassin! The mark goes on a random opponent. Just tap on the marked enemy to target them, and boom. It's pretty close to a defense ignore effect. Focus Fire them down! (Dota2 anyone?) Her talent is useful in an earth squad, but not much use anywhere else.

Priest

Ara

Leader: At the start of every turn, recover 1000 HP to the hero with the lowest current HP and boosts their DEF by 50%
ULT: Greatly heals the HP of the 3 most injured allies.
Talent: Water type allies receive 10% less damage.

Arguably the best healer in the game. If you got her, feel free to jump up and down. Her leader skills ensure the survival of your squishiest unit, although at high levels, units tend to have over 20k HP. Still pretty great nonetheless. Her love for injured allies continues on in her ULT, which can be better or worse than a whole team heal, depending on the situation. You wouldn't want Ara's ULT when your whole team is about to die, right? The important thing in the heal amount. In potion terms, if Linda's was compared to a small potion Ara's heal would be that of a large potion. If you use her together with Yan, her REC boost will see your units healing yo full HP in an instant. Her 10% damage reduction is not good, but better than nothing. But she's uglier than Linda

Linda

Leader: Small change of fully recovering fury gauge after using ULT.
ULT: Heals all allies and removes paralysis.
Talent: Boosts healing ability.

Rather plain compared to our Ara, but her healing is not too shabby with her talent unlocked and she can heal her whole team, too. She's the best whole team healer, remember that and use her accordingly. Her leader skill is trash, just don't bother with it. The chance is too low to be of any practical use. A lot of thunder units have "When HP is full" effects, so she's a must have in order to synergise with them. On top of that, she's pretty damn cute.

Angel

Leader: Makes allies immune to Curse and bones, reduces incoming damage by 15%
ULT: Boosts allies' damage for 30% for 2 turns, recovers 20 fury for all allies. (230% is most likely an error)
Talent: Reduces cost by 4, increases HP of light type allies by 8%

Damage reduction by 15%? it's probably the highest non-element-specific damage reducing leader skill, it might be worth using against strong enemies. Her ULT: wow an attack buffer! and recovers fury! Besides her leader skill, she's a priest built for offense. Her cost reduction can be useful for those early-game players who are struggling with cost (her 4* reduces cost by 3). Fury boosting is very useful, it might get you that clutch heal off or the last bit of damage you need to finish off an enemy.

Yan

Leader: Every turn, all allies deal 8% more damage, stacks every turn up to a total of 10 times/80%.
ULT: Fire attack to all enemies.
Talent: Boosts all allies' REC.

Ignore the current English description, it's wrong. A leader skill with HUGE damage potential. She would be a great leader for long drawn out fights. It resets every stage and does not continue throughout the quest. Her ULT is an attack, despite being a priest. And it's weak. Don't know why that's there. Her Talent, however, basically gives your healer a buff, increasing the amount your allies get healed for. In other words, you don't have to use multiple healers to ensure good healing.

Honorable Mentions

Ron

Leader: Boosts EXP gained by Allies after battle by 50%
ULT: Dark attack to all enemies.
Talent: Reduces cost and boosts ULT damage to himself.

Our beloved starter. Due to the fact you get his evolution materials as you progress through the game, he'll be the first 5* you'll ever get (unless you did a few summons :P). His EXP boost id good for raising unit levels while raiding for materials, so take good care of him. Of course, he gets completely blown out of the water by War Maiden and well, he just becomes an EXP slave when you start getting better units because his stats aren't very good either.

Thank you for reading! That concludes the post (for now). Tell me if there are any others you think deserves a mention?

Also, PM me for any typos, don't shame me by mentioning it in the comments