To hit 500+, get the best weapon you can find, and save items that add to damage (I found two with +200). After equipping the item/s just do a random rouge killing quest. You should be able to hit 500+ now.
Here's my tip: Activate Void when he's just above 990000 health. Avoid getting him below it. After he uses one of his turns, and his health is !below! 990000 health, hit him with subversion. He'll try and heal himself, only to kill himself in the process.
visarobot, please don't spam. Leave the comments for people who actually have something to say about the game.
Nice game, good graphics, can't wait for 2.