Screaming Malice

AC 18 (natural armor)
HP 125 (10d12 + 60; bloodied 62)
Speed 30 ft., swim 30 ft.
Initiative Dex +5 (15), Insight +1 (11), Perception +1 (11)

Proficiency +4; Maneuver DC 17
Skills Athletics +9, Perception +5 (+1d8), Stealth +9 (+1d8)
Saving Throws Str +5, Dex +5, Con +10, Int –3, Wis +5, Cha –2
Damage Vulnerabilities psychic
Damage Immunities bludgeoning, piercing, and slashing from nonmagical weapons
Condition Immunities charmed , frightened , prone
Senses darkvision 120 ft., passive Perception 19

Cephalic Quincunx. Vaster and grander than any conventional hydra, the Armageddon beast’s five tarry heads stretch out from its scaled body in a quincunx formation. The screaming malice has five Medium heads which can share the body’s space and which each have a reach of 5 feet. Whenever the screaming malice moves, only its body moves unless otherwise stipulated. When it starts its turn, it can reposition its heads to spaces of its choice within 30 feet of its body, which does not provoke opportunity attacks . If a head is ever more than 30 feet away, it falls off and dies harmlessly, and a replacement head grows at the end of the screaming malice’s next turn, sharing its space. Each head can be dealt damage by attacking it, but the heads and body share a single hit point pool. Individual heads cannot be destroyed this way. While it has more than one head, the screaming malice cannot be blinded, deafened, stunned, or knocked unconscious.
The screaming malice can take four reactions per round, but the extra three can only be used to make opportunity attack bites with heads, and each head can only make one opportunity attack per round.

Legendary Resistances (3/Day). If the screaming malice fails a saving throw , it can succeed instead.
Magic Resistance. The creature has advantage on saving throws against spells and other magical effects.
Magic Weapons. The creature’s weapon attacks are magical.
Psychic Vulnerability. Whenever the screaming malice takes psychic damage, one creature of the attacker’s choice becomes immune to its Emotive Wail for 24 hours.

ACTIONS

Multiattack. The creature uses Emotive Wail, then for each of its heads, it uses either Predatory Pentad or Cranial Biogenesis.
Bite. A head with fangs as long as your arm gnashes its tarry maw around you. Psychic currents excite your heightened emotions, and your synapses falter, bringing you to the ground in a heap. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 9 (1d8 + 5) piercing damage. If the target is charmed , frightened , or experiencing intense magical emotions (such as from hideous laughter, rage, or Emotive Wail), it must succeed on a DC 18 Wisdom saving throw or fall prone .
Cranial Biogenesis. The head rips itself free from a long neck. Bones crack and tendons snap together as the skull reshapes itself into a semi-autonomous, reptilian predator, covered in the same tar as the greater beast. The screaming malice moves one of its heads up to 30 feet and detaches and transforms that head into a malice spawn. The spawn acts immediately after each of the screaming malice’s turns, including the turn in which the spawn was created. A new head regrows at the end of the screaming malice’s next turn. The creature cannot use this action if it already has three active spawn.
Emotive Wail. Many mouths stretch open wide, then roar in unison. Wispy shadows coalesce around the Armageddon beast’s heads, full of hallucinatory detail and textures. Your heart races with uncertainty before finally settling on one self-destructive impulse. It screams, penetrating deafness and magical silence. Each non-malice creature within 120 feet of the screaming malice and not currently affected by its Emotive Wail takes 2 (1d4) nonlethal psychic damage and must succeed on a DC 18 Wisdom saving throw or suffer a random effect for 1 minute. Each creature rolls a d6 to determine how it is magically affected:
1–2: Fear. The creature is frightened .
3–4: Fascination. The creature is charmed. The effect ends if the creature takes any damage.
5–6: Euphoria. The only action that the creature can take is Dash . A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature’s saving throw is successful or the effect ends for it, the creature is immune to the Emotive Wail for the next 24 hours.
Predatory Pentad. The screaming malice moves one of its heads up to 30 feet and makes a Bite attack with that head.

REACTIONS

Devour Heroics. Your triumph may be short-lived, as ravenous jaws come careening towards you. When another creature rolls a critical success, the screaming malice can use Predatory Pentad.

LEGENDARY ACTIONS

The screaming malice 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. It regains spent legendary actions at the start of its turn.
Feed on Fear. You glimpse a terrifying hallucination of your death. One frightened creature within 120 feet of the screaming malice must make a DC 18 Wisdom saving throw . If it fails it takes 9 (1d6 + 6) psychic damage, and the screaming malice can move 10 feet.
Lure. You see the object of your heart’s desire nestled within its writhing necks, and you stagger gape-mouthed toward it. One charmed creature within 120 feet moves a distance equal to its Speed, its path chosen by the screaming malice. The creature is then incapacitated for as long as it remains charmed by the screaming malice.
Never-Tangling Quintet. The screaming malice uses Predatory Pentad.