The monsters of Faerun version is 6HD, judging by its powers I would say an level adjustment of 5-6, so total ECL of 11-12<br/><br/>The Fiendish Codex I Hordes of the Abyss version is 10HD and slightly better powers so at least level adjustment of 6, maybe 7 for a total ECL of 16-17<br/><br/>Just my opinion, if you compare it to the succubus. (Yochol CR is also one higher as the succubus, so it's level adjustment should at least be comparable to it)