Your first team should avoid having debuffs, otherwise you'll give the boss many extra turns. You should run a Defender to apply Defense Down for 4 turns. Your second team needs debuffs. You don't have to run a team that uses debuff as DPS (like a burn comp or Gnosis Beth). Just make sure you can maintain at least one debuff.
Difficulty

Revenant Dragon Harshna

Lv. 80Immunities
Skills

Rotten Claws
Single TargetAttacks an enemy. Inflicts Poisoned on the target for 1 turn(s). Prioritizes attacking the enemy's front line.

Vicious Chill
CD 4All EnemiesAttacks all enemies. Inflicts Poisoned 2 times on all targets for 2 turn(s). (Irremovable)

Struggle of the Dead
CD 5All EnemiesAttacks all enemies. When attacking, if the caster is granted a dispellable debuff, inflicts Frozen on all targets for 1 turn(s). (Irremovable) This attack penetrates 30% of the target's Defense.

The Awakened
When the caster is granted a dispellable debuff, Weakness Gauge cannot be reduced.
Grants a special effect to the enemy team based on their class.
Striker: Increases Attack by 30%
Mage: Increases Critical Damage by 50%
Defender: When performing an action, inflicts reduced Defense on the Boss for 4 turns
Ranger: When performing an action, deals 3% damage of the Boss's Health
Healer: Increases Priority recovery efficiency by 50%

Defying Death
All AlliesWhen an ally is inflicted with a debuff, increases Priority of the caster by 100%. At the end of the turn, when the caster is granted a dispellable debuff, recovers Weakness Gauge by 20. Curse damage does not exceed a maximum of 5000.

Frozen Dragon of Phantasm Harshna

Lv. 110Immunities
Skills

Relentless Destruction
Single TargetAttacks an enemy, and removes 1 debuff(s) from the caster. Prioritizes attacking the leftmost enemy.

Slaughtering Flutter
CD 4All EnemiesAttacks all enemies, and removes all buffs from the target. This attack penetrates 30% of the target's Defense. Right after using this skill, does not trigger an enemy's Counterattack, Revenge, or Agile Response.

Advent of Ruin
CD 5All EnemiesAttacks all enemies. When attacking, if the caster is not inflicted with a debuff, ignores 100% of the target's Defense.

Harbinger of Ruin
If the caster is not inflicted with a debuff, Weakness Gauge cannot be reduced.
Increases Weakness Gauge damage taken from enemies granted Stealth by 100%.
Grants a special effect to the enemy team based on their class.
Striker: Increases Attack by 30%
Mage: Increases Critical Damage by 50%
Defender: When hit by a single attack, grants Stealth for 2 turn(s)
Ranger: Increases Effectiveness by 100%
Healer: Increases Priority recovery efficiency by 50%

Ultimate Scale
Reduces Weakness Gauge damage taken from Skill Chains by 50%. At the end of the turn, when the caster is not inflicted with a debuff, recovers Weakness Gauge by 20, and reduces the enemy team's Chain Points by 50. Fixed damage cannot exceed 30000.
Tips and teams below are written for Extreme League.
Phase 1
- Your first team should avoid having debuffs, otherwise you'll give the boss many extra turns.
- You should run a
Defender to apply for 4 turns.
Phase 2
- Your second team needs debuffs. You don't have to run a team that uses debuff as DPS (like a burn comp or Gnosis Beth). Just make sure you can maintain at least one debuff.
- Any
Ranger with 
Rampaging Caracal or 
Heartunder's Blade equipped can do the job. - Any good AoE
Mage can do it too with 
Noblewoman's Guile.
Phase 1 — Recommended Characters
Defender options to apply for 4 turns.
Demiurge Luna, Maxwell, Regina, Demiurge Astei, Gnosis Dahlia, Gnosis Domine
Other strong DPS without debuffs.
and .
Phase 2 — Recommended Characters
and good damage.
Strong CP generation, teamwide , huge WG damage.
Can maintain debuff like and . Also provides .
Bell Cranel, Vlada, Maxie, Ember
specialist.
, and (be sure to apply the last one AFTER the boss's S2).

































