Here are his attacks, and how to avoid them:
Attack 1: Fin Slap
Deviace will swim-jumps backward, and starts slapping foward with his fins, covering a small distance and dealing damage to any players he hits. To avoid this, just stay away from him.
Attack 2 (At five-sixths health): Forward Bite
Deviace's eyes will glow red for a while and his mouth on top of his head will enlarge. He then bite forward, dealing damage to players in the way. To dodge it, just duck/squat down, or stay behind it.
Attack 3 (At five-sixths health): Chomp Bite
Deviace swim-jumps backward and his head mouth will enlarge. He then chomps down in front of it, dealing to players caught in it, and continous damage to them until they escape from him. To avoid it, best is to stay behind him.
Attack 4 (At five-sixths health): Rock Blast
Deviace's eyes will glow red and then roll for a while. His head mouth will then open up and blasts some a stream of rocks. Every rock will deal to the player when it hits. To avoid this, just stay behind him. This attack is blockable too.
Attack 5 (At half-health): Stop Spell & Rock Blast
Deviace's eyes will glow red, creates a purple spell circle around and tries to close in to the players. Any players caught in it will be stopped, rendering them unable to move/attack/block, and Deviace coutinues the attack with a Rock Blast attack. If no one get caught in the spell circle for a while, Deviace will disperse it and continues moving around the screen. To avoid this, stay away from him and try to jump over him when needed. If it seems impossible to escape, block before he stop you, that way the Rock Blast attack can still be avoided.
Attack 6 (At half-health): Pillar Thrust
Deviace's eyes will glow red and his head mouth will open. A stone pillar will then be sent flying forward out of it, dealing damage to any players it hits. To dodge this, simply duck/squat down.
Attack 7 (At half-health): Pillar Fall
Deviace will swim-jumps backward and his head mouth opens, pointing upward. A stone pillar is then launched into the air. A short while later, it will crush down onto the ground, dealing damage to players below it, and splitting into halves. The two halves will continue to deal damage to any player they hit, until they disappear. To avoid this, just stay away from him. This attack is blockable too.