Invidiak
CREATURE 7An invidiak has no physical body and is born out of a deep sense of envy over this lack. An invidiak only feels properly "alive" when they're possessing a host. In many cases, an invidiak remains dormant in such a host, spending months, even years, observing from within and building up its influence over the host slowly, so as to cause as much long-lasting despair and emotional trauma to the host's friends and family as possible.
Lengthy Possessions
An invidiak can possess a favored host for an unlimited amount of time, and over the course of years their influence can result in their host gaining strange new and unique supernatural powers that grow from this spiritual corruption. Such powers only function as long as the possession lasts; if the invidiak is forced out of the body, these powers vanish and don't return, even if the invidiak later re-possesses the same host. These unique invidiaks are generally much more powerful than the typical one presented here.
If an invidiak attempts to possess a creature and the creature rolls a critical success on its saving throw to resist Possession, or if an invidiak's possession of a creature is ended prematurely, such as via a successful Dispel Magic, the invidiak takes 6d6 mental damage and cannot use possession for 24 hours.
Each invidiak has a type of creature they prefer possessing, chosen from aberration, animal, beast, or any humanoid (such as dwarf, elf, or human)—in most cases, the favored type of target is human. When an invidiak casts Possession on a favored host, the duration of possession increases to unlimited, and the effect lasts until dispelled or until the invidiak dismisses it.
An invidiak leaves no body behind when using Possession.