When you use a tangle of rat tails on a tomb rat, it turns into a tomb rat king. Mafia applies +ML to the new monster, but +ML should not be applied. A simple fix is to put its HP, Def, and Atk inside [] in monsters.txt. It's possible that there's something more generic going on that could be accounted for, but Eleron pointed out that KoL handles this differently (using javascript) than other monster-changing-mid-combat things (CLEESH uses a new page load), so it probably isn't necessary to make the code more generic. Tomb rat kings can't be copied, so they will always be encountered by using tangles and will always ignore +ML (at least until KoL introduces some new mechanic).