Teraphim tannoth are a possible inhabitant of a strange-larva-hellish seal. They are one of the most dangerous possible monsters that may be found under this type of seal. They are notable both for their high physical damage output and their slow petrification attack.
Slow petrification attack
A hit from one of these attacks has a 1/3rd chance of attempting to apply the slow stoning effect. If you are defending and don't have a lizard corpse in open inventory the effect is automatically applied, otherwise it is only applied 10% of the time. If you are defending you will begin turning to stone as if you had heard a cockatrice's hissing. Monsters will be turned to stone instantly.
This close-range breath attack deals 1d6 damage per 3 levels of the attacker (8d6 for the typical teraphim). If a target caught in the blood splash has blood (as most player characters do) it takes additional damage equal to its level. In addition, all targets' inventories are wet with blood. Finally, monsters become crazed, berserk, and confused, while the player character is inflicted with the apostasy madness and loses 1d6 sanity.
While afflicted with apostasy, the character will sometimes lose 10 alignment record points. If this leaves them with a negative alignment record, they will sometimes lose a point of maximum alignment (if max alignment is greater than 10) or anger their god. If you contract this madness, it is important to keep your sanity up to avoid smiting.
In addition, there is a percentage chance equal to the amount of sanity lost that a character won't be able to pray each turn.
Tannin (plural tanninim) is an ancient Hebrew word meaning "sea monster" (or sometimes "serpent," and sometimes translated as "dragon"). Ancient Semitic religions used sea monsters to symbolize primordial chaos, and sometimes evil (see also Tiamat/the Chromatic Dragon.
The etymology of tannah is a bit less clear; however, it seems to be the feminine form of tan ("jackal"). It appears to symbolize desolation, loneliness, and abandoned places. English-language sources tend to claim that it means "dragon" and is the feminine form of tannin, but this appears to be a mistranslation. Regardless, dNetHack uses the word as though it were the feminine form of tannin.
Teraphim is an ancient Hebrew word of uncertain meaning. While some traditions held that it meant "disgraceful things," it is believed to actually refer to "idols" or "household gods" though context suggests that it had a more specific meaning.