Actions

Multiattack. Asmodeus makes four attacks using Ruby Rod, Chilling Gaze, or a combination of the two. He can replace one of the attacks with Hellish Smite.  

Disease Equalizes Lesser and Greater Men (Recharge 5-6). Melee Weapon Attack: +# to hit, reach 5 ft, one target. On a hit, the target is poisoned. At the end of each of the poisoned target’s turns, the target must make a Constitution saving throw. If the target succeeds on three of these saves, it is no longer poisoned, and the effect ends. If the target fails three of these saves, the target is no longer poisoned, but choose one of the diseases outlined in the Contagion spell description. The target is subjected to the chosen disease for 7 days. Because Asmodeus's touch induces a disease in its target, any effect that removes a disease or otherwise ameliorates a disease’s effects apply to it.

Nessul Seed. With an action, Asmodeus can prepare a Nessul Seed - a fragment of his own diabolical heart - for implantation, plant it within the heart of another creature, or remove it from another creature. Each of these requires a separate action. On a turn where Asmodeus is extracting a Nessul Seed from a creature, Asmodeus is unable to take reactions or legendary actions. To plant a Nessul Seed in a creature, Asmodeus makes a melee attack against that target within 5 feet of him. +21 to hit. On a hit, the target becomes possessed. At the end of each of the possessed target’s turns, the target must make a WISDOM?CHARISMA? saving throw. If the target succeeds on three of these saves, it is no longer possessed, and the Seed is not ejected from its body but also has no further effect on the creature. If the target fails three of these saves, its attitude toward Asmodeus becomes friendly and it treats any course of action Asmodeus says a Suggestion as per the spell. After 3 successes or 3 failures, the possessed condition ends regardless of the outcome.

Reach Heaven Through Violence. Melee Weapon Attack: 1d20+21 to hit , reach 5 ft., one target. Hit: 21 2d8+12 necrotic damage, which also reduces the target's hit point maximum by the damage taken. This damage can't reduce a target's hit point maximum below 1. Any effect that removes a disease allows a creature's hit point maximum to return to normal.

Reactions

Ruby Absorption. As a reaction to being the sole target of a spell, Asmodeus can attempt to absorb the spell into the Ruby Rod. Asmodeus rolls (1d20 + 2), and if the result is higher than (10 + spell level), the spell is nullified.

Rebuke Divinity. In response to taking radiant damage from a creature within 60 feet of you that you can see, Asmodeus forces the attacker to make a DC DC Wisdom saving throw or be stunned. until the end of its next turn.

Soul Reaper. When Raphael reduces an enemy's hit points to 0, he can sever the soul from their body. With no soul to motivate it, the affected creature has Disadvantage on Attack rolls and all Ability checks until its soul is restored. Contact with Asmodeus can dislodge the soul from his possession. A Soul Wrenched creature can reclaim its soul by successfully scoring a melee spell attack or melee weapon attack against Asmodeus.

Legendary Actions

Legendary Action Uses: 3. Immediately after another creature's turn, Asmodeus can expend a use to take one of the following actions. Asmodeus regains all expended uses at the start of each of their turns.   Cast a Spell. The archdevil uses their Spellcasting feature to cast an available spell. If the spell normally requires concentration, it lasts for the full duration instead.   Channel Ruby Rod. The Ruby Rod has 66 charges. Asmodeus may spend its charges to cast one of the following spells from it, with a spell save DC of 20: Lesser Restoration (3 charges), Wall of Force (7 charges), Greater Restoration (12 charges), Chain Lightning (15 charges), Prismatic Spray (23 charges), Globe of Invulnerability (33 charges). Cleansing Flame. Asmodeus selects one spell effect on himself or a creature of his choice within 60 feet. That spell effect is removed. Strike (Costs 2 Actions). Asmodeus makes a Ruby Rod attack or commands one of his underlings to immediately use their reaction to make a single attack.   Call Underling (Costs 3 Actions). Asmodeus summons an allied fiend in an unoccupied space that he can see. He chooses which fiend he calls.

Lair Actions

Asmodeus's Lair Actions are replaced by Villain Actions. Time-based Villain Actions take effect on initiative count 20 (losing initiative ties), but others take effect when their triggering condition is satisfied.

 

When an enemy expresses true despair: All that you desire is just beyond all that you fear. Asmodeus summons Mephistopheles to prepare an infernal contract with Calamus.

 

Round 1: Immutable Word of Law Benefits the Lawmaker. "Kneel. That was not a request." Asmodeus invokes an ancient, absolute command. All creatures of his choice within 120 feet must make a DC ## Wisdom saving throw. On a failure, they are charmed until the end of their next turn. While charmed this way, they cannot target Asmodeus with attacks, spells, or harmful effects.

 

Round 3: The Paths to Oblivion and Exaltation Are the Same Road. Hellish chains lash at five creatures of Asmodeus's choice within 90 feet of him. The targets must each make a Wisdom saving throw (DC ##). On a failed save a chain restrains the target and deals 4d10 psychic damage. For every 5 that a target misses the DC by, an additional chain wraps around the target (i.e., fail by 1 = 1 chain; fail by 6 = 2 chains). The chains are manifestations of the target's fears, which Asmodeus becomes aware of in a general sense (i.e., if the target fears death, darkness, losing all their friends, etc.). While restrained, the target takes an additional 22 (4d10) psychic damage at the start of each of their turns and then may repeat the saving throw. The DM may award advantage on this saving throw if the player describes how the trapped creature attempts to overcome or reconcile their fears.

  Round 5: Absolute Authority Asmodeus demonstrates his complete dominion over all devilkind. He selects one spell, ability, or statement made by another creature since the start of the last round and alters its outcome. He can rewrite one spoken sentence (no longer than 10 words) said in the previous round. This can alter spell effects, orders, or even truths: Change a failed save into a success (or vice versa) Reverse a spell’s target or effect Cause a healing effect to instead deal necrotic damage Rewrite the target of a wish-like effect  

At 333 HP: Reality is Relative. The first time Asmodeus is bloodied (i.e., falls to half his maximum hit points) and every round thereafter, reality bends to Asmodeus's unbreakable will. Choose one of the effects below. It remains in effect until the next initiative count 20: Gravity reverses within a 120 ft aura around Asmodeus. Creatures must make a DC 15 spellcasting ability check in order to cast a spell. Failing the check does not expend the spell slot A 20 ft area around Asmodeus becomes heavily obscured by unquiet souls.

  At 100 HP or less: At Once Final and Forever. Asmodeus taps into the core of his command over the Dark Dimension. He regains all used Innate Spellcasting (3/day) uses. Each enemy must succeed on a DC ## Constitution saving throw or be blinded by the diabolic radiance for 1 minute. A creature blinded by diabolic radiance may repeat the saving throw at the end of each of its turns. Additionally, he receives the following boons for the next 1 minute or until he reaches 0 HP with his Regeneration disabled. Friendly Devils gain advantage on attack rolls and saving throws while within 30 feet of him. His spell and ability saving throw DCs increase by #.

Regional Effects

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

 

The Devil's Greeting. Within 500 miles of his lair, an illusory version of Asmodeus (as if he has cast the Project Image spell) appears. Asmodeus attempts to communicate with any characters and decipher their intentions. If they're hostile, Asmodeus pretends to prepare himself for combat, in an effort to make the character's waste their resources.

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

Usual Tactics

One of Asmodeus's core beliefs is that fighting is a final resort - and, if it is used at all, it should be a means to an end. Throughout a battle, Asmodeus holds back just enough to show his opponents what a spectacularly terrible choice they have made by challenging him. He will offer deals to the combatants mid-combat (e.g., “I’ll spare your ally if you swear allegiance to me”). Accepting gives temporary power or healing but comes with long-term narrative consequences.