Stage 1: He's throwing fireballs! Hint text says to catch the fireballs and throw them back. My method: Run up to him and beat on him with the wrench. Every time he hits me, the shock aura thing paralyzes him for a while. And makes him take 4x damage from the wrench. Oops!
Stage 2: He's... electric I think? And summons a swarm of security drones to help him. So I peg him with security bullseye, and they kill him for me while I hide. I think that was probably the recommended method.
Stage 3: He's ice or electric, whichever the one he wasn't in stage 2. He summons a swarm of splicers with machine guns to help him. As noted in previous entries, machine guns can't hit the broad side of a barn, so I ignore them and beat on him with the wrench, like in stage 1.
Then I grow old and die. No, really, that's the ending. Presumably this happens years later, after a long full life. NO SEQUEL FOR YOU!
I also started playing Patapon, where you control a gang of spear-chucking eyeballs by playing four-note drum beats over and over and over until your fingers are too tired to move. I'm pretty sure I've screwed up my tribe already, though, since I spent all my money and rare materials making a really powerful sword-wielder, who promptly got eaten by a giant lizard in his first fight.