The signed list and the tile captcha.
Anubis defends the login against automation and gives you a way to catch a clone.
The login shows six tiles, each a tilted character, next to a decoy input field whose name rotates on every page load. A bot fills the wrong field and trips the trap. You read the tiles and type into the visible real field. This frustrates automated phishing kits that cannot solve the tiles or track the rotating field names.
Anubis signs its mirror list with a PGP key you can verify. Verifying the signature proves an address came from the market and nobody edited it. The addresses on this page are checked against that signed list, and there is usually more than one onion live at once so a flood on one does not lock you out.