User blog comment:Daniel Baran/Search Developments: Big Picture/@comment-4528041-20120508195723/@comment-957747-20120510193724

Using AdBlock is within Wikia's ToU. Hiding Wikia's ads via AdBlock or CSS is well within your right as a user.

That said, the only breach of ToU is when you choose to hide ads for all users with CSS. You stop Wikia from showing ads to other users; not just yourself. That's where the ToU break is done.