Nightmare Wraith (5e Creature)
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Large undead, chaotic evil
Damage Resistances acid, cold, lightning, thunder; bludgeoning, piercing, and slashing from nonmagical attacks that aren't silvered
Incorporeal Movement. The nightmare wraith 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.
Confer Fire Resistance. The nightmare wraith can grant resistance to fire damage to anyone riding it.
Magic Resistance. The nightmare wraith has advantage on saving throws against magic and magical effects.
Life Drain. Melee Weapon Attack: +7 to hit, reach 5 ft., one creature. Hit: 22 (4d8 + 4) necrotic damage. The target must succeed on a DC 14 Constitution saving throw or its hit point maximum is reduced by an amount equal to the damage taken. This reduction lasts until the target finishes a long rest. The target dies if this effect reduces its hit point maximum to 0.
Hooves. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 13 (2d8 + 4) bludgeoning damage plus 3 (1d6) necrotic damage and 3 (1d6) fire damage.
Shadow Stride. The nightmare wraith and up to three willing creatures within 5 feet of it magically enter Shadowfell from the Material Plane, or vice versa.
A nightmare taken to Shadowfell and spent so much time as to where it is warped by the very nature of the plane as to where it becomes embodied by a wraith.