Special Equipment. Kostchtchie carries Gorynya, a powerful magic warhammer.

Innate Spellcasting. Kostchtchie’s innate spellcasting ability is Charisma (spell save DC 20, +12 to hit with spell attacks). It can cast the following spells, requiring no material components.

• At will: command, darkness, detect magic, ice storm, sleet storm

• 3/day each: cone of cold, disintegrate, fire shield (cold damage only), wall of ice

• 1/day: control weather

Legendary Resistance (3/day). If Kostchtchie fails a saving throw, it can choose to succeed instead.

Magic Resistance. Kostchtchie has advantage on saving throws against spells and other magical effects.

Magic Weapons. Kostchtchie’s weapon attacks are magical.

Unholy Aura. An unholy aura surrounds Kostchtchie out to a radius of 40 feet. A creature who enters or begins their turn in the area must make a DC 20 Wisdom saving throw. On a failed saving throw, the target is frightened for 1 minute. While frightened, it is paralyzed. A frightened target can repeat the saving throw at the end of each of its turns, ending the effect on a success.

Actions

Multiattack. Kostchtchie makes two attacks with Gorynya.

Gorynya. Melee Weapon Attack: +18 to hit, reach 15 ft., one target. Hit: 29 (4d8 + 11) bludgeoning damage, or 33 (4d10 + 11) bludgeoning damage if used with two hands, plus 22 (4d10) force damage. If the target is a creature, it must make a DC 23 Strength saving throw or be knocked prone.

Summon (1/day). Kostchtchie summons 1d12 dretches, 1d6 glabrezus, 1d6 hezrous, 1 marilith, or 1 balor. The summoned demon appears in an unoccupied space within 60 feet of Kostchtchie, but can’t summon other demons. It remains for 1 minute, until it or Kostchtchie is slain, or until Kostchtchie takes an action to dismiss it.

Legendary Actions

Kostchtchie can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature’s turn. Kostchtchie regains spent legendary actions at the start of its turn.

Cold Burst. Kostchtchie causes a burst of cold to coalesce around it. Creatures within 10 feet of it must make a DC 20 Constitution saving throw. On a failed saving throw, the targets take 13 (3d8) cold damage, or half as much damage on a successful one.

Sunder (Costs 2 Actions). Kostchtchie slams Gorynya on the ground. The area within 15 feet becomes difficult terrain. Each creature that is concentrating must make a DC 23 Constitution saving throw. On a failed save, the creature’s concentration is broken. In addition, all creatures must make a DC 23 Dexterity saving throw or fall prone. Kostchtchie is immune to these effects.

Freeze (Costs 3 Actions). Kostchtchie chooses one target it can see within 120 feet to make a DC 20 Constitution saving throw. On a failed saving throw, the creature takes 22 (4d10) cold damage and is restrained. At the start of its next turn, the target must repeat the saving throw. On a failed saving throw, it is fully encased in ice and is petrified. On a successful saving throw, the creature suffers no other effect.

Lair Actions

On initiative count 20 (losing initiative ties), Kostchtchie can take a lair action to cause one of the following effects; Kostchtchie can’t use the same effect two rounds in a row:

Rage. Kostchtchie chooses any number of creatures within its lair to make a DC 20 Wisdom saving throw; Kostchtchie must be aware of intruders within its lair, but he does not need to see the targets. Until initiative 20 a creature who fails the saving throw is filled with blinding rage and uses its actions and movement to attack the nearest creature that it can see.

Corpse Cleanup. Kostchtchie destroys any corpse within its lair; its does not need to see it in order to destroy it. That creature is incapable of being brought back from the dead absent a true resurrection or wish spell.

Curse. Kostchtchie chooses one creature that it can see within 60 feet to make a DC 20 Constitution saving throw. On a failed saving throw, the creature is cursed; the curse ends early if removed with magic such as remove curse. While cursed, the creature is vulnerable to cold damage.

Regional Effects

The region containing Kostchtchie’s lair is warped by his magic, creating one or more of the following effects:

Cold. The area within 6 miles of Kostchtchie’s lair is unnaturally cold, even if that would not make sense; during the day the temperature hovers around freezing, while at night the temperature plummets to below 0 degrees Fahrenheit.

Ire. The various beasts and creatures that inhabit the area around the lair are more inclined to be hostile, filled with wrath, even attacking other creatures who would not normally be their prey.

If Kostchtchie dies, these effects fade over the course of 1d10 days.

Gorynya

Weapon (warhammer), artifact (requires attunement)

Gorynya is an overly large warhammer, wrought of black iron, covered in frost. It stands almost 4 feet tall from rounded pommel to the head, which bears a spike at its top and two blunt, unfinished faces. It is remarkably devoid of ornamentation but bears what appears to be centuries’ worth of chips, nicks, and dried blood.

Attunement. Gorynya cannot be attuned to as long as Kostchtchie, the Demon Lord of Wrath, is on the same plane of existence as Gorynya. For you to attune to the weapon, you must first slay an ally of like alignment in a fit of blind rage and remain unremorseful for doing so.

Oversized. Gorynya is much larger than a normal warhammer. You can only wield Gorynya two-handed if your Strength score is 18 or higher. To wield Gorynya one-handed, your Strength score must be 22 or higher.

Magic Weapon. You have a +3 bonus to attack and damage rolls made with Gorynya. Gorynya also functions as a mace of terror and a staff of frost.

Overwhelming. You deal an additional 4d10 force damage when you hit with Gorynya, and your target must succeed on a Strength saving throw or be knocked prone. The DC for this saving throw is 8 + your Strength modifier + your proficiency bonus.

Cold Bones. You have resistance to cold damage while you are attuned to Gorynya, and rime and frost coat every visible surface within 10 feet of you.

Destroying Gorynya. In order to destroy Gorynya, you must first beg forgiveness from all those you have slain with the weapon, and they must forgive you for the acts you committed while attuned to the weapon. If that is done, then Gorynya shatters into rubble forever.

large

fiend

cr22

tome-of-horrors

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