Boss Traits:
1. Your heroes get a 10% damage boost for each enemy unit they hit.
2. Damage is reduced while under Healing Reduction effects.
 
Strategy: Since the boss summons minions and your damage goes up with each enemy hit, use AoE (Area of Effect) heroes to maximize those damage bonuses. Throw out Healing Reduction cards to cut down the boss's damage output and make your team tougher to kill.
The ideal heroes for this strategy are:

Battle Details:
Use Thia's skill before the boss's second ability to slap on Healing Reduction and lower the boss's damage output.

After the boss's third skill, unleash your Ultimate skills in this specific order: Lossenia → Hvitar → Vidimir.

 
You must follow this exact sequence, or your damage output will drop significantly.

Skill sequence settings:

Good luck out there, hit as hard as you can, and may you all snag the Affinity Solvent!