Blizzard may terminate this Agreement (and your access to the Game) with or without notice for any reason, or for no reason.
Just because it's written there doesn't mean it has any power if it's illegal. No ToS may supersede your consumer rights. Blizzard just crazy statements and clauses to make it that much harder and longer to contest it in court against them, as the practice now in the US is for big companies to just bankrupt smaller plaintiffs by making the court process take too long and require the aid of very high paid lawyers. They do know such statements, as the one quoted above are total BS and cannot survive a real court battle, but the agreement is full of other BS that will make it very hard for an individual to actually win, as a lot of companies got burned during the Clinton administration, when this entire "Everyone can sue everyone" trend started.
Now small people have actually worse chances at winning than before as they get strangled by the big corporations with stuff that is very expensive to fight against.
You will, actually win big money if you do win, and this is one nice thing to it, so I wish you best of luck.
Here is what you can use in your favor if you should decide to go to court.
1. You did not accept or sign this ToS before purchasing the game. You weren't presented with this ToS at the moment of purchase. Legally, this is very unethical marketing and is a solid ground to contest the agreement and win. Blizzard may argue that the ToS and EULA are published on their site, but this is still a violation of consumer rights, as they are still withholding vital information from the consumer, by publishing it in different places, scattered, obfuscated and in a hard to comprehend manner.
2. Application of methods, which change a customer's financial behavior - you are forced to either accept the EULA and ToS at the moment of starting the game, or not play, but you are not entitled to a refund in case you disagree with what is outlined in there, and in such a manner they are holding you hostage with your own money, essentially pressuring you to accept the agreements, or forfeit your money, which is another violation of consumer rights, so even tho you have accepted the ToS, you have done it under pressure from them, a situation in which you ended due to them using the practice in #1, as they are essentially selling the product in one place and keeping the essential legal documents in another place, in this case the Internet. Now, things might turn out to be more complicated if you bought the game online, but still you may argue about the shape in which it was presented, how it was presented, and the overall incomprehensible, hard to understand nature of the ToS and EULA, which require a significant amount of time on behalf of the customer to fully read and understand.
3. The provisions of Sections 4, 5, 8, 11, and 12-17 shall survive any termination of this Agreement. You need to look that one up closer, as it does sound shady. You shouldn't be forever bound by the provisions of a terminated agreement.
4. Essentially, the part about forfeiting refunds on all your items on your Battle.net account, including pre-ordered items is a "fine" Blizzard are imposing on you should you decide to terminate the agreement, since the agreement also mentions you may not resell your Battle.net account to others, so they are illegally pressuring you to stay stuck with them forever, or forfeit everything you have. Again breach of consumer rights.
5. You should sue in Europe if you are from Europe, as the rights of the consumer and of the individual in court and your chances are better there.
