Bilge Rat Buccaneer: Use Blinding Light to disorient them when they try to cast Banana Rampage
Ashvane Invader: Use Divine Shield or Blessing of Spellwarding to drop stacks of Stinging Venom Coating
Sergeant Bainbridge/Chopper Redhook
Blessing of Spellwarding or Divine Shield to immune bombs if they’re about to go off
Don’t walk in bombs on the ground. If the boss is chasing after you, make him run through bombs on ground.
Dread Captain Lockwood
On the ground there will be big circles appearing. Don’t stay on those circles. Pick up the thing left on the floor and use it to force boss back. Keep her slow / root at all times or she will House of Pain - Jump Around.
When big waves appear, hide behind the big statue in the middle of the room. Don’t walk on the ice.
If you’re tank always go melee range of Demolishing tentacle (kill this one first as specified by u/sindeloke). Then help the dwarf get out of his personal anime episode by killing tentacles grabbing him. If you have dot on you go away from friends so you can get dispelled without feeding your friends to sharks.