Cremator

Only spawns in the Magma Barracks.

Shoots a radnom shotgun-blast-like-spread of bombs with the white cirlce, much like the Wandering Vagrant's attacks to show where they'll hit.

This attack is easily dodgeable, but can hit you on the way up to its target zone.

He spawns swimming in the lava at the bottom of the map like a giant turtle.

Unless you posses a non-linear attack you pretty much have to swim in the lava to kill him.