Paimon (water) gains a protective buff that blocks damage; remove it by killing the shadow mini-bosses that spawn in the centre. Mob waves are stopped by activating the central totem.

Water

Endgame

Ice Dragon Alzanor

Two pre-rooms (6 buttons/10 mobs, then 6 buttons/8 mobs). In the boss fight stay close to the frost deflectors to survive the ice attacks.