make sure your reflexes are fast because once you summon him, he will attempt to eat you. when that fails, he will launch various beams which you must dodge for a bit(his aim is very very very precise) and if you survive that, he spawns some bots to attack you. if you manage to defeat all the bots, the game ends and it will say you are the winner...
seriously he lets you make a wish either for strength(i think its a 1 mil power gain) immortality(for half a minute) or friendship(just to get a wishpoint tho its better to wish for the other 2)