Druj

The Druj is the Iranian spirit of the Lie, adapted by Zoroastrianism for the nature of Ahriman and his divs. The term is also employed for incorporeal undead, cognate with Norse draugr and (thematically) French phantôm. The Druj Nasu bends the boundary between demon and undead; Pathfinder assigns them to divs.

Which brings us to /tg/. Frank Mentzer's "Basic Dungeons & Dragons" dredged up the concept for his Companion Set, in the Spirit class.

The druj has ridiculously mighty AC (although since you need +2 weapons to hit any Spirit, there's an offset) and 14 Hit Dice (although since you need 4th-level spells to affect a Spirit, that's likely one more offset).

The Mentzer druj is basically a moving Vecna body part: eye, hand, or skull - but (implicitly) noncorporeal. The eye has a gaze attack (for paralysis) but otherwise only inflicts poison damage if it touches you; the hand can grapple for continuous damage; the skull has a terror-effect and bites. The eye and the skull float; we're not explicitly told how the hand moves, but it probably crawls.

Druj work alone unless "a Lich or more powerful member of the Sphere of Death" commands it, and even such can gather no more than five at a time. The former means even Nightshades aren't awesome enough to enlist a druj team. The latter means demon but, you know - the Sets won't admit it yet.

As a Spirit, the druj is toxic and will spoil your shit in a 30' radius - and if it touches you and you flunk your Save, the poison is deadly. Luckily, just like real lies, the druj is powerless in sunlight and invisible.

As for why an ambulatory bodypart is named like an Indoeuropean ghost and stuck in the "Spirit" class, well... good question, and similar questions were raised about the Mentzer Revenant. Probably why the whole "Spirit" idea was abandoned whilst the Nightshade, being awesome, lives on.