You pull it, it takes 100 NP from you, and you have a chance to get an avatar each time you pull. (Small chance) I've spent 4k on it, got the av. I know people who have spent 5mil on it and still not gotten it...
Don't lol at me. If you go on the AC, a few people have tried for the lever for a year plus, spending nearly all their NP. I'm not saying it's not a waste of np (because it is) but this kid named Jed documented it all for about a year and finally got it after 4.7 mil i think. he made a big deal about it about two years ago on the ac.
I remember all the fuss when people found out about how much he spent. I suggest, if you're going for the avatar, set aside one amount, try until that's gone, then forget it ever existed.