The horned devil is flagged to only appear in Gehennom, but no lawful creatures can be randomly generated there - thus, they are effectively never randomly generated. This trait also occurs with barbed devils and the erinys, though all three are still eligible to be generated via gating by other major demons.
Horned devils are still generated in graveyards; in addition, the lairs of Asmodeus and Baalzebub will each contain a horned devil upon normal level creation. Another horned devil appears within Moloch's Sanctum, placed just outside the temple near its southeast corner.
The horned devil is considered the weakest of the major demons by the game, with a lower monster difficulty than even the barbed devil despite having a better AC. It is also ranked as weaker than the water demon, which has weaker attacks and a comparable AC; this is likely because the water demon is faster, can swim, and may potentially appear much earlier.
Despite their solid AC, horned devils are somewhat slower than an unhasted player, and a fast character with good AC of their own and a blessed weapon that is well-enchanted and/or silver will have relatively little trouble dispatching one. Horned devils are also weak to cold attacks, and a wand or cone of cold can eliminate them in one or two zaps.
Horned devils are a decent source of tridents and bullwhips for those looking to utilize either.
These devils lack any real special abilities, though they
are quite difficult to kill.