Actions

Multiattack. Dispater makes four attacks using his Wrought-Iron Tower. He can replace one of the attacks with Superheat Metal or Father of Discord (if available).

Father of Discord. (1/day) Dispater magically spreads doubt and discord, affecting up to 12 creatures of his choice within 60 feet. A target that fails a DC 22 Wisdom saving throw believes that one of their allies is a traitor, acting against the group's best interest. A target will take hostile or defensive actions against the perceived traitor. This effect lasts for 24 hours unless dispelled. If Dispater damages an affected creature, the spell ends for that creature. Creatures that can't be frightened are immune to this effect.

Wrought-Iron Tower. Melee Weapon Attack: +18 to hit, reach 10 ft., one target. Hit: 20 (2d8 + 11) bludgeoning damage plus 10 (3d6) fire damage to good-aligned creatures. Dispater may replace the bludgeoning damage with damage of a type that the target is vulnerable to instead.

Superheat Metal (Recharge 4-6). Dispater targets a metal object he can see within 90 feet of him. The metal glows white-hot, burning all that touches it. If the object is worn or held by a creature, the creature must succeed on a DC 20 Dexterity saving throw to drop the object or take 36 (8d8) fire damage. If the object is attached to a creature, or they couldn't feasibly drop it, they automatically fail the save. The object returns to room temperature at the end of Dispater's turn.

Bonus Actions

Molten Teleport. Dispater teleports up to 30 ft to an unoccupied space that he can see.

Reactions

Shrapnel Spray. To use this reaction, Dispater must have access to a metal object (either held in his hand or unattended within 10 feet of him), which is destroyed when the reaction takes effect. When Dispater takes damage from a source within 60 feet that he can see, he launches metal debris in a 10-foot-cone. All creatures within the area of effect must make a DC 20 Dexterity saving throw, taking 36 (14d4) piercing damage on a failed save, or half as much damage on a successful one. Metal launched from this reaction embeds itself into surfaces that it touches.

Legendary Actions

Legendary Action Uses: 3. Immediately after another creature's turn, Dispater can expend a use to take one of the following actions. Dispater regains all expended uses at the start of each of his turns.

Intrusive Thoughts. Dispater targets one creature he can see within 60 feet of him. The creature must succeed on a DC 22 Charisma saving throw or have disadvantage on its next attack roll, ability check, or saving throw. Creatures immune to effects that would sense its emotions or read its thoughts (such as those affected by Mind Blank) are immune to this effect.

Flesh to Iron (Costs 2 Actions). Melee Spell Attack: +13 to hit, reach 5 ft., one target. Hit: 33 (5d10 + 6) force damage, and the target must make a DC 20 Constitution saving throw. On a failed save, the target's flesh begins to harden, and the creature's movement speed is halved. A creature restrained by this action must make another Constitution saving throw at the end of each of its turns. If it successfully saves against this spell three times, the spell ends. If it fails its saves three times, it is turned to iron and subjected to the petrified condition for the duration. The successes and failures need not be consecutive; keep track of both until the target collects three of a kind. If the creature is harmed by Flesh to Iron again while still partly iron, the rest of the creature also turns into iron. The petrification lasts until the creature is freed by the greater restoration or other magic. If the creature is physically broken while petrified, it suffers from similar deformities if it reverts to its original state.

Shatter Psyche (Costs 2 Actions). Dispater targets one creature affected by the charmed, frightened, or paranoid conditions. That creature takes 36 (8d8) psychic damage and must make a DC 22 Intelligence saving throw or become stunned until the end of its next turn.

Call Underling (Costs 3 Actions). Dispater summons an allied Stone Juggernaut (TOA , p 231) in an unoccupied space that he can see.

Lair Actions

On initiative count 20 (losing initiative ties), Dispater can take one lair action to cause the following effects; he can't take the same lair action two rounds in a row:

Deceitful Whispers. Dispater whispers to a creature he can see within 30 feet. The target must make a DC 22 Wisdom saving throw. On a failed save, the target has the charmed condition until the start of their next turn and must use their reaction immediately to make an attack against one of the Dispaters's enemies, chosen by the Dispater.

Forge Ahead. 1d3 columns of iron erupt from surfaces of Dispater's choice within 120 feet. Each column is 5 feet wide, 10 feet tall, has 40 HP and immunity to psychic and poison damage. These columns remain until destroyed, or until Dispater uses this lair action again.

If You Wish to Know the Greatest Evil Simply Gaze into a Mirror. Until the next initiative count 20, all metal surfaces and objects become polished and reflective. When a creature that can see starts within 30 feet of a reflective creature must make a DC 22 Wisdom saving throw or see a personal failing in its reflection and become frightened. Unless surprised, a creature can avert its eyes to avoid the saving throw at the start of its turn. If the creature does so, it has disadvantage on attack rolls and cannot see Dispater until this lair action ends. If the creature looks at its reflection in the meantime, it must immediately make the save.

Regional Effects

The region containing Dispater's lair is corrupted by his presence, which creates the following effect:

Din. Within 6 miles of the lair, the sound of metal working is near inescapable. Any creature attempting a short or long rest may do so, but must make a DC 20 Constitution saving throw afterwards. Failure negates any benefits of the rest.

If Dispater dies, the effect fades over the course of 1d10 days.