X-Men Legends II: Rise of Apocalypse

you can never kill him, only defeat him, when you take down his health he will go into the main power source thingy and replenish, when he does that YOU go into the same power source thingy and gain extra powers, then just destroy all the generators in the locked rooms, you don't need a key, just run straight into them, just follow the wire on the floor and watch out for the extra exp bonus in one of the rooms

Do your best or use Nightcrawler, Iceman, Sunfire, and Jaggernaut.

that's it....