Board Thread:Support Requests - Community Management/@comment-5138040-20131122040227/@comment-4018164-20131122055437

You can request via Special:Contact/general for disabling anonymous editing for a week or so. The user(s) that may be up to this would probably leave.

An IP range block is probably not gonna matter, but i'm pretty sure that MediaWiki can detect contributions that use proxies. Maybe you can ask Wikia's support to disable this instead for a while (i'm not sure if it's better than an ordinary IP disabling as some contributors may be using proxies as well).