Prevent MediaWiki from being spammed

My MediaWiki site is currently under the spammers attack. I get around 10 spam pages registered daily.

What I've I already done:

1. Only users with confirmed emails can create/edit pages.
2. ReCAPTCHA widget. Captcha displayed on the actions:
   1. 'edit' - triggered on every attempted page save
   2. 'create' - triggered on page creation
   3. 'addurl' - triggered on a page save that would add one or more URLs to the page
   4. 'createaccount' - triggered on creation of a new account
3. Proxy blocker
4. SpamBlacklist

What else can I do to stop the spam?