All his attacks are just spamming specials so you can just keep running circles around him or around the perimeter of the arena if there's too many enemies. Reefslider explosions can't reach you if you're close to him and if he knocks you airborne just glide away to the side.

Keep the outer perimeter painted in case you need to flee and preemptively paint under where the spawn orbs will move to slow them and damage them instead of letting them regenerate health.