Josias said:
No offence to you, but: What a loser your brother is!
C'mon, he dropped out of High school and spent many of the states and probably also your money just because he's lazy and wants to play World of Warcraft.

Get the boy off his drugs by simple buying him an old laptop running Win 95/98...... Remember, he's like a kid or animal, you have to gain his respect to make him obey you. You have clearly lost all his respect by: 1. Bribing him to quit Wow. 2. Faling in every other method of parenting, since he's turned out so.
I'm sorry to be so harsh on you, but it's sad a human should sink so low.
Wait WAIT
WAIT.
I'm quoting Josias not to pick on him/her, but to highlight a theme in all these replies.
Look at the OP's original comments!!
He is on anti-depressents been through 4 councelors and was walked though high school by the special education program.
I think that spending all his time on WoW is the last of his concerns!! If one is depressed and lacks the motivations and will power to do anything, it is VERY common to turn to something that one feels they can be good at and accomplish. Many other people turn to drugs, alchohal, or any number of other unhealthy things to stamp out the pain of lonelyness and uselessnes. Likely he is quite good at WoW, and has players there that accept him and work with him.
One of my 21 y/o Co-Workers is in a 200+ person Wow clan, he says he is one of the youngest. He thinks the youngest is 20 or so, most are late 20s to mid 30s, and there are a number of couples. This isn't a kids game past a certain level.
Everyone here thinks that WoW is the root of the problem. I'm going to seriously bet that there are far deeper problems here, and that WoW is an outlet for an already troubled mind.
No, I am not a WoW player, nor do I intend to be. However be careful if you argue with me without knowing the severe effects of Depression, because I do know them.
I'm not sure taking WoW away from him is going to cure anything. The deeper problems need to be solved first.
DO NOT try and lure him away from WoW by getting him involved with girls or parties, that will get him in FAR more trouble. You can trust me on that one too.
To the OP: You are unlikely to understand fully what is goin gon with your brother. That is okay. But try not to be angery with him too much or take revenge on him or try and force him out of it. Your brother is sick, and needs to be well again.
God bless this kid.
~Tyler