With their spindly limbs, arms instead of legs (giving them the predatory slink of a jungle cat or mandrill), and distinctive flaps of skin(?) over their faces, avataranas look like things out of a video game—and guess what, it’s a horror title. (And since you guys know that world a lot better than me, you’ll have to tell me which one.)
Lots of rakshasas want to manipulate mortals, but avataranas skip the details and just flat-out possess them, actually melting into their bodies. The Occult Bestiary details their usual M.O. after that point:
[T]hey patiently work their way up social ladders, finding more impressive and influential individuals to possess […] but their viciousness increasingly shows. Only when others turn against their victims do avataranas release their control, leaving their prey to deal with the ramifications of the rakshasa’s acts.”
So first the issue is detecting the rakshasa, then the issue is successfully confronting the outsider without killing the host, and ideally doing so in a public setting so that the host’s innocence in the rakshasa’s vile doings can be confirmed. And it’s that last part that’s the tricky bit. Reputations don’t respond to Heal checks, and in a game world without mass media, Diplomacy and Profession (Barrister) checks will only get you so far…particularly against a monster who’s probably been using mental magic left and right for weeks, if not months or years, on the very people the PCs are trying to win over. Good luck!
Adventurers are being fêted by vanaras after services to one of the ape-men’s gurus, only to be framed for the murder of an occultist by the end of the banquet. They are kept on the run and sleepless throughout the vanara temple complex, with friends becoming enemies the second the rakshasa takes possession of them.
The Choker King is neither a choker nor a doppelganger. He is an avatarana…and some of the chokers even whisper that he shaped them in his own image. (The doppelgangers are too proud to whisper such things, but privately some believe it.) The chokers say you never know when the king will chose to ride one of them (which also means that in game terms he is Advanced enough to possess aberrations as well as humanoids). Certain doppelgangers have pieced together there is a pattern to his killings, and quake with the knowledge that all their race’s pitiful schemes and murders might be simply a smokescreen to hide his real ends. The chokers simply know that if you displease the Choker King, he’ll likely torture and murder your whole clutch out of hand…and if you think the rack or crucifixion are awful, you really haven’t seen them until you’ve seen them inflicted upon creatures whose limbs stretch more than twice their own height…
In a sudden reversal of policy, the head of the British Museum declares all Egyptian artifacts to be pagan works that corrupt the national spirit, and demands they be smashed. The head Egyptologist is horrified and demands a party of adventurers investigate. (And since they are owed a substantial bounty for recovering many of these artifacts from under the nose of Napoleon’s armies, the adventurers have a vested interest in doing so.) The British Museum head is actually under the possession of an avatarana who does not wish Britain to unlock the secrets of the artifacts, as they could open the door to occult powers with the potential to rival his own. Of course, if the adventurers successfully drive out the rakshasa, they may have traded one evil for another, because the Egyptology department has been thoroughly infiltrated by worshippers of the Great Old Ones—cultists who very much want to see those artifacts not only preserved and catalogued, but also put to use.
—Occult Bestiary 49