Planar Bestiary
Moietans are sometimes found near dimensional anomalies and portals; however, they never pass through such portals themselves.
This bizarre creature is easy to miss, given that they're only a few inches long. But once they somehow siphon dimensional scale from a target, they crackle with yellow light as they feed on that stolen size reduction.
Hungry for dimensional energy, moietans feed on the change in ratio in living victims. As the moietan nourishes themself, their target shrinks away to nothing.
Seemingly from some distant, incomprehensible dimension, these creatures fear dimensional travel and avoid passing through portals or other planar interfaces. Not necessarily because doing so kills them, but because regardless of the planar destination of the portal or interface, moietans are instead banished back to their unknowable home.
Motive: Hungers for liberated scalar energy
Environment: Anywhere in the multiverse, alone or in nests of two or three
Health: 12
Damage Inflicted: Minor wound (3 points)
Armor: 1
Movement: Immediate; short when flying
Modifications: Speed defense as level 5 due to tiny size
Combat: The moietan's tendril attack inflicts damage and, on a failed Might defense task, causes the target and their equipment to shrink to two-thirds their normal size. The reduced victim descends one step on the damage track, and the moietan regains 3 points of health.
Each additional hit on the same victim inflicts damage and, on a failed Might defense task, further shrinks them an additional third of their original size and pushes them another step down the damage track, and the moietan regains another 3 points of health.
If a target descends all three steps on the damage track from moietan attacks, they die. Their remains are no larger than a grain of dust.
Each time a victim ascends one step on the damage track (perhaps by expending a recovery roll, or through the use of magic by themself or an ally), the victim regains one third of their original size.
If killed, a moietan rises again in 1d6 + 1 days. Permanently destroying one requires sending their remains through a portal or other dimensional interface or otherwise moving the body between planes.
Interaction: The moietan is a predator and has no fear of death. The only thing that drives them off is the use of dimension-traveling magic.
Use: An empty ship pulls into harbor, its crew missing. An unwholesome insectile buzzing emerges from the hold. Townspeople decide to call in adventurers to check out the situation.
GM Intrusion: Instead of dying, a character who descends three steps on the damage track finds their change in scale has opened a new "dimension" of the world to them. Unfortunately, that means tiny ants and other insects that notice them are essentially all horrible monsters that must be fled or fought.