If the külmking moves through another creature, it can use a bonus action to corrupt that creature’s soul. The target creature must make a DC 16 Charisma saving throw. A creature paralyzed by the külmking has disadvantage on this saving throw.

On a failed save, a creature suffers from terrible and violent thoughts and tendencies. Over the course of 2d4 days, its alignment shifts to chaotic evil. A creature that dies during this time, or after this shift is complete, rises 24 hours later as a külmking. The corruption can be reversed by a remove curse spell or similar magic used before the creature’s death.

On a success, a creature is immune to the külmking’s Corruption for the next 24 hours.

The külmking can pass 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.

If the külmking moves at least 20 feet straight toward a creature and then hits it with a hooves attack on the same turn, that target must succeed on a DC 16 Strength saving throw or be knocked prone. If the target is prone, the külmking can make one hooves attack against it as a bonus action.