Ahriman

Aura of the Fallen God. Ahriman can use a bonus action to active his infernal aura and it remains in effect until he uses another bonus action to contain it. The aura extends out in a 60-foot radius from him. Each creature that starts or ends its turn in the aura takes 28 (8d6) fire damage.

Colossal. Ahriman’s space is 200 feet by 200 feet. Any creature Large or smaller can enter his space and any such creature must be within Ahriman’s space to be considered adjacent. In addition, any creature Large or smaller can only target Ahriman’s body and tail unless it is able to fly, the attack range is greater than 15 feet, or it is using the climb onto a bigger creature rules in the DMG. Additionally, any creature adjacent to a Medium or smaller target that is hit by one of Ahriman’s melee attacks must make a DC 30 Dexterity saving throw or take the same damage as the initial target. If Ahriman is targeted by an area of effect, the DM will determine if the effect targets his head, tail, body, or a combination of his parts. If multiple parts are affected, each body part takes damage separately. Additionally, he as advantage on saving throws against being pushed or knocked prone.

Divine Might. Ahriman's attacks and effects ignore the resistances and immunities of creatures CR 25 and below. Ahriman's attacks and effects targeting creatures of CR 26-35 ignore resistances and treat immunities as resistance (condition immunities provide advantage in lieu of immunity).

Divine Reflexes. If Ahriman succeeds on a saving throw against an area of effect, he may spend his reaction and move outside the area, suffering no damage, conditions, etc. from the effect. Ahriman must have enough move distance to get out side the area of effect. He may also spend legendary move actions in addition to the reaction to gain the distance required to move outside the area of effect.

Dominating Presence. When targeting a creature of CR 40 or below Ahriman’s enthrallments ignore resistance and creatures with immunity have advantage on their saving throw instead. In addition, Ahriman can use a bonus or legendary action to exert precise control of creatures he has charmed.

Fatal Flaw. If Ahriman's hit points drop to 0, his essence does not return to his domain, instead of Discorporation, Ahriman's body and essence is annihilated from reality.

Innate Spellcasting. Ahriman’s spell casting ability is Charisma (spell save DC 30, +25 to hit with attack spells). He can innately cast, requiring no components from the following:

At will: animate dead, contact other plane (always succeeds), detect magic, dispel magic, fear, geas, hold monster, ice storm, mass suggestion, plane shift, suggestion, telekinesis, teleport, thunderwave, wall of fire, wall of ice

3/day each: arcane gate, blight, chain lightning, charm person, creation, divine word, dominate monster, etherealness, forbiddance, forcecage, greater invisibility, hellish rebuke, resurrection, symbol, telepathy, true polymorph

1/day each: astral projection, gate, holy aura, power word heal, power word kill, mass heal (1000 hit points), meteor swarm, true resurrection, wish

Legendary Resistance (7/day). If Ahriman fails a saving throw, he can choose to succeed instead.

Magic Immunity. Unless Ahriman wishes to be affected, he is immune to spells of 9th level or lower, and he is resistant to and has advantage on all other spells and magical effects.

Magic Weapons. Ahriman’s attacks are treated as +5 magical weapons.

Power of the Primordial God. Any of Ahriman's attacks that do fire, psychic & force damage does maximum damage.

Scales of the Fallen God. When Ahriman is targeted by a Magic Missile spell, line spell, or a spell that requires a ranged attack roll, roll a d6. On a roll of 1-2, the functions normally, on a roll of 3-4, the spell is deflected and Ahriman is unaffected. On a roll of 5-6, Ahriman is unaffected and the effect is reflected back at the caster as though it originated from Ahriman, turning the caster into the target.

Siege Monstrosity. Ahriman deals triple damage to objects and structures.

Multiattack. Ahriman can use his Cataclysmic Majesty. He then makes two bite attacks, or one tail attack, or one immolate foe attack.

Bite. Melee Weapon Attack: +25 to hit, reach 30ft., one target. Hit: 171 (42d6 + 24) piercing damage. If the target is a creature, it is Grappled (escape DC 37). Until this grapple ends, the target is Restrained, and Ahriman can't bite another target.

Tail. Ahriman makes one of the following attacks:

Sting. Melee Weapon Attack: +25 to hit, reach 160 ft., one target. Hit: 213 (42d8 + 24) piercing damage. If the target is a creature, it must succeed on a DC 30 Constitution saving throw or take 210 (20d20) poison damage and be poisoned for 12 hours.

Sweep. Ahriman swings his tail in a 160-foot cone. Each creature in the area must make a DC 30 Dexterity saving throw or take 213 (42d8 +24) bludgeoning damage, pushed 60 feet, knocked prone, and stunned.

Immolate Foe. Ranged Spell Attack: +25 to hit, range 960 ft., one target. Hit: 88 (16d10) fire damage and the target must make a DC 30 Constitution saving throw, losing all resistance to fire damage for 24 hours on a failure.

Dark Eruption. Magma erupts from a point on the ground that Ahriman can see within 360 feet of him, creating a 150-foot high, 30-foot radius geyser. Each creature in the geyser’s area must make a DC 30 Dexterity saving throw, taking 72 (16d8) fire damage and 72 (16d8) bludgeoning damage on a failed save, or half as much damage on a successful one.

Infernal Aura. Ahriman unleashes his primordial power. Each creature within 120 feet of him must succeed on a DC 30 Dexterity saving throw or take 171 (42d6 + 25) fire damage and be knocked prone. Ahriman can then fly up to half his flying speed.

Prismatic Blaze. Ahriman exhales prismatic fire in a 600-foot cone. Each creature in that area must make a DC 30 Dexterity saving throw, taking 416 (64d12) fire damage on a failed save, or half as much damage on a successful one.

Scorching Ash. Ahriman creates a 60-foot radius sphere of Scorching Ash centered on a point he can see within 480 feet of him. The sphere spreads around corners, is lightly obscured, and last 7 (2d6) rounds. Each creature that starts its turn in the cloud must succeed on a DC 38 Constitution saving throw or be poisoned until the start of its next turn. While poisoned in this way, a creature is incapacitated.

Divine Hellfire (Recharge 5-6). Ahriman exhales fire in a 900-foot line that is 10 feet wide. The first creature in the line must make a DC 30 Dexterity saving throw, taking 312 (48d12) fire damage plus 312 (48d12) force damage on a failed save, or half as much damage on a successful one. In addition, each creature within 40 feet of the initial target must make a DC 30 Dexterity saving throw, taking 52 (8d12) fire damage plus 52 (8d12) force damage on a failed save, or half as much damage on a successful one.

Cataclysmic Majesty. Each creature of Ahriman’s choice within 480 feet of Ahriman and aware of him must succeed on a DC 30 Wisdom saving throw or be stunned for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Divine Influence. If Ahriman is targeted for a ranged weapon or ranged spell attack, he adds +5 to his AC, if the attack misses then he can telekinetically move the closest creature to him (aside from the creature who targeted Ahriman for the initial attack) to take the hit instead of him. If the attack still hits, then this reaction does not take effect.

Divine Rebuke (3/day). When Ahriman is the target of a ranged weapon or spell attack, divine hellfire recharges and he can use a reaction to use it immediately.

Ahriman can take 7 legendary actions. Only one legendary action option can be used at a time and only at the end of another creature’s turn. If Ahriman has unspent legendary actions at the end of the round, he may spend and immediately use his remaining legendary actions. Ahriman regains spent legendary actions at the start of his turn.

Bite. Ahriman makes a bite attack.

Detect. Ahriman can make a Wisdom (Perception) check.

Move. Ahriman can move up to half his movement speed.

Regenerate. Ahriman regains 50 hit points.

Spellcasting. Ahriman can cast a spell.

Tail Attack. Ahriman makes a tail attack.

Teleport (Costs 2 actions). Ahriman can teleport 240 feet to an unoccupied space he can see.

Infernal Attack (Costs 3 actions). Ahriman makes an Infernal Aura attack.

Mass Spellcasting (Costs 3 actions). Ahriman can cast up to 3 spells.

Divine Hellfire (Costs 7 Actions). Ahriman instantly recharges and uses his Divine Hellfire attack.