Blizzard will then choose finalists to perform live at BlizzCon 2013 for a chance to win. Finalists will be chosen based on talent, live performance, humor, entertainment, originality, creativity, and strong Blizzard theming, of course! Submissions are now open on the BlizzCon contests page -- you can check out the page to enter, or take a look at the official rules as well.
As for prizes, according to the official rules, the first place winner will receive $4,500 USD, second place gets $3,500 USD, third place will get $2,500 USD, and fourth place will receive $1,500. In addition, all acts that are chosen as finalist acts will each receive $500 USD. Even if you don't enter the contest yourself, it sounds like the live show should be incredibly entertaining for attendees. If you'd like to enter, better hurry -- submissions are due by August 6. Good luck to all who enter!