Alastor

Alastor are the most common minor devils, found across all nine planes of Hades, where they often advise the rather slow-witted gargoyle hordes that guard the lower realms, and sometimes carry messages between the different orders of devils. Their sharp minds and cunning have earned these imp-like creatures the nickname evil geniuses, and they are much sought after as first-rate familiars.

Once a day each, for an hour at a time, an alastor can turn into a big black-haired dog, speak in tongues or become invisible, and it can sense magic within ten feet. Good spell casters may find one hard to manage, since unless it gets to do something evil or at least spiteful fairly often, it will slyly twist any order it dislikes. Otherwise it is very useful for carrying messages, spying and small alchemical chores such as stirring mixtures or fetching ingredients, where it may raise its master's odds of making a thaumaturgic substance by up to five percent. Once a month it can be made to reveal the given name of one lesser or greater devil, which it does happily, hoping its master will lean ever more on the powers of Hades. It also regenerates one hit point every hour.