DybbukMedium fiend (demon)
Incorporeal Movement. The dybbuk can move through other creatures and objects as if they were difficult terrain. It takes 5 (1d10) force damage if it ends its turn inside an object.
Magic Resistance. The dybbuk has advantage on saving throws against spells and other magical effects.
Spellcasting. The dybbuk uses Divinity (Cha) to cast spells (spell save Difficulty 12, +4 to hit with spell attacks). It has 4 mana, a mana limit of 1, regains all expended mana when it finishes a long rest and regains half its total mana when it finishes a short rest. It knows the following spells:
At will: teleport (augmented to 3 mana)
1 mana: fear
1/day: phantasmal force
Violate Corpse. Once on its turn, while possessing a corpse, the dybnuk can make the corpse do something unnatural, such as vomit blood, twist its head all the way around, or cause a quadruped to move as a biped. Any animal or humanoid that sees this behavior must succeed on a Difficulty 12 Will saving throw or become frightened for 1 minute. The frightened creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. A creature that succeeds on a saving throw against this ability is immune to Violate Corpse for 24 hours.
Tendril. Melee Weapon Attack: +6 to hit, reach 1 m. Hit: 13 (2d8 + 4) necrotic damage. If the target is a creature, its maximum health is also reduced by 3 (1d6). This reduction lasts until the target finishes a short or long rest. The target dies if this effect reduces its maximum health to 0.
Possess Corpse (Recharge 6). The dybbuk disappears into an intact corpse it can see within 1 meter of it. The corpse must be Large or smaller and be that of an animal or a humanoid. The dybbuk is now effectively the possessed creature. Its type becomes undead, though it now looks alive, and it gains a number of temporary health equal to the corpse’s maximum health in life.
While possessing the corpse, the dybbuk retains its health, personality, Intelligence, Wisdom, Charisma, telepathy, and immunity to poison damage, exhausted level, and being charmed and frightened. It otherwise uses the possessed target’s game statistics, gaining access to its knowledge and proficiencies but not its class features, if any.
The possession lasts until the temporary health are lost (at which point the body becomes a corpse once more) or the dybbuk ends its possession on its turn (no action required). When the possession ends, the dybbuk reappears in an unoccupied space within 1 meter of the corpse.
No concoctions, maneuvers, or spells
All creatures in this system should have maneuvers or spells. You should add some maneuvers or spells to this creature. If you do so, please make a suggestion on github so I can finish adding maneuvers and spells to all creatures via https://github.com/mlenser/kryx-rpg-issues/issues/9.