Jack Norman/gameplay

The Ultimate Abyss can absorb a substantial amount of fire and can be difficult to beat without understanding his attacks. Whenever his back opens, that's the cue he's about to teleport. When he does warp, he tends to appear directly behind you so fire at him to interrupt his lunge.

Eventually, the Ultimate Abyss will start leaving an afterimage whenever he teleports, in an effort to trick you into attacking thin air; the real mutant will always emit purple smoke in this instance and mostly appears behind you when he does this.

The next stage of attacks is that the Ultimate Abyss will start creating multiple duplicates - each one will attack you and then disappear without actually hitting. Remember to fire at the one emitting smoke.

When his health reaches critical levels, the Ultimate Abyss begins using its most powerful attack and will rapidly create several duplicates at once to confuse you whilst he performs a damaging charge. Be ready to attack the real Ultimate Abyss as soon as you see the smoke.

In his late attack phases, heavy damage will cause Ultimate Abyss to briefly fall to his knees; use this moment to get some clear shots of the weak point on his back.

Keep repeating this strategy and you will eventually defeat the Ultimate Abyss and complete the game.