Ancient Grand Matriarch Tenebralis Bloom

Aura of Endless Decay. A 40-foot radius aura of necrotic energy surrounds the Grand Matriarch. Creatures that start their turn in this area must make a DC 21 Constitution saving throw or take 8d8 necrotic damage, have their speed halved, and suffer disadvantage on attack rolls and saving throws until the start of their next turn. This damage bypasses resistance to nonmagical damage.

Infernal Maw. Grappled creatures take 6d8 necrotic damage and 4d6 acid damage at the start of their turn. Creatures reduced to 0 hit points in this manner are absorbed into the Grand Matriarch and cannot be resurrected without a Wish spell or divine intervention.

Shadow Sovereignty. While in dim light or darkness, the Grand Matriarch is heavily obscured to creatures without truesight and has advantage on all attack rolls.

Corrupted Genesis. When reduced to 0 hit points, the Ancient Grand Matriarch explodes in a 60-foot radius burst of necrotic energy. All creatures in the area must make a DC 21 Constitution saving throw or take 12d10 necrotic damage and be blinded for 1 minute. On a successful save, creatures take half damage and are not blinded.

Burrowing Nightmare. The Grand Matriarch can burrow through any surface as though it were loose earth. While burrowed, it is considered heavily obscured and gains advantage on its next attack roll. It can burst from the ground as part of an attack, dealing 8d6 piercing damage to all creatures within 20 feet.

Hellish Majesty. The Grand Matriarch has resistance to fire, radiant, and cold damage.

Multifaceted Eyes. The Grand Matriarch has developed clusters of glowing, prismatic eyes that grant it darkvision out to 240 feet and truesight out to 120 feet.

Telepathic Dominion. The Grand Matriarch can telepathically communicate with any creature that understands a language within 300 feet. Its whispers impose disadvantage on Insight checks against it.

Environmental Subjugation. Over the course of 12 hours, the Grand Matriarch corrupts a 1/2-mile radius area, transforming it into a necrotic wasteland filled with hostile plant-like beasts & plant creatures under its control.

Multiattack. The Grand Matriarch makes four attacks: one with its Oblivion Bite and three with its Tendril Lash.

Oblivion Bite. Melee Weapon Attack: +15 to hit, reach 15 ft., one target.
Hit: 6d12 + 8 piercing damage plus 6d8 necrotic damage. The target must succeed on a DC 21 Strength saving throw or be grappled (escape DC 21). If the target is grappled, the attack deals an additional 4d6 acid damage.

Tendril Whip. Melee Weapon Attack: +15 to hit, reach 50 ft., one target.
Hit: 5d10 + 8 bludgeoning damage. The target must succeed on a DC 21 Dexterity saving throw or be restrained.

Pillar of Decay (Recharge 5–6). The Grand Matriarch creates a pillar of necrotic energy in a 20-foot radius within 120 feet. Each creature in the area must make a DC 21 Constitution saving throw or take 10d10 necrotic damage and become paralyzed for 1 minute. Creatures can repeat the saving throw at the end of their turns.

Consuming Bloom. The Grand Matriarch causes its flowers to release a hypnotic display of lights in a 60-foot radius. All creatures that can see it must make a DC 21 Wisdom saving throw or be charmed for 1 minute. While charmed, creatures are incapacitated and cannot move.

Grasping Shadows. The Grand Matriarch summons spectral tendrils in a 30-foot radius. All creatures in the area must succeed on a DC 21 Strength saving throw or have their speed reduced to 0 until the end of their next turn.

Command Minions. The Grand Matriarch commands corrupted plants and plantlike creatures in its aura to attack specific targets. Up to 5 plants or plant-like beasts within 60 feet take an immediate action.

Lure Prey. The Grand Matriarch emits a faint, hypnotic glow from its tendrils. One creature within 60 feet that can see it must make a DC 21 Wisdom saving throw or be compelled to move 15 feet closer to the bloom on its next turn.

Spawn Juvenile Blooms (Recharge 5-6). The Elder Matriarch expends a portion of its corrupted essence to spawn up to 5 Juvenile Tenebralis Blooms in unoccupied spaces within 60 feet of it. These Juvenile Blooms act on the Grand Matriarch's initiative and obey its telepathic commands.

Fortify Bloom (Recharge 5-6). The Grand Matriarch channels its energy to heal and fortify all allied Tenebralis Blooms within 60 feet. Each affected Bloom regains 8d10 hit points and gains a +2 bonus to AC and saving throws for 1 minute.

Writhing Defenses. When a creature within 30 feet attacks the Grand Matriarch, it can use its reaction to make a Tendril Whip attack against the creature.

Flicker of Shadow. When targeted by an attack in dim light or darkness, the bloom can impose disadvantage on the attack roll as shadowy tendrils obscure it. This can be used once per short rest.

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

• Tendril Strike. The Grand Matriarch makes a Tendril Whip attack.
• Necrotic Pulse (Costs 2 Actions). The Grand Matriarch emits a wave of necrotic energy in a 40-foot radius. All creatures in the area take 6d10 necrotic damage and must succeed on a DC 21 Constitution saving throw or be stunned until the end of their next turn.
• Darkness Unleashed (Costs 3 Actions). The Bloom creates an area of magical darkness in a 30-foot radius centered on itself. The darkness lasts for 1 minute or until the Bloom dismisses it as a bonus action. Creatures inside the darkness take 2d8 necrotic damage at the start of their turns.
• Blossom of Oblivion (Costs 3 Actions). The Grand Matriarch releases a burst of radiant necrotic energy in a 100-foot radius. All creatures must make a DC 21 Wisdom saving throw or take 10d10 necrotic damage and become frightened for 1 minute. A creature can repeat the saving throw at the end of its turns to end the effect.
  
  

Ancient Grand Matriarch Tenebralis Bloom (Mythic Variant)

Mythic Traits
When the Ancient Grand Matriarch Tenebralis Bloom is reduced to 0 hit points for the first time, it doesn’t die or release its Corrupted Genesis ability. Instead, it sheds its outer layer in an eruption of necrotic energy, restoring itself to full hit points and activating its Mythic Form.

• All previously summoned Tenebralis Blooms are healed to full hit points and gain a +2 bonus to attack rolls, damage rolls, and saving throws.
• The environment within 300 feet becomes fully corrupted: the ground is difficult terrain, creatures take 4d10 necrotic damage at the start of their turn while standing on it, and visibility is reduced to 30 feet due to an oppressive mist.

Mythic Actions

The Grand Matriarch gains the following additional abilities while in its Mythic Form:

Corruption Cascade (Costs 2 Actions). The Grand Matriarch targets a 60-foot radius area within 120 feet. The ground erupts with shadowy vines and necrotic energy. All creatures in the area must make a DC 22 Strength saving throw or be restrained. While restrained in this area, creatures take 6d10 necrotic damage at the start of their turn. A restrained creature can use its action to make a DC 22 Strength check to escape.

Spawning Bloom (Costs 3 Actions). The Grand Matriarch creates 1d4 Juvenile Tenebralis Blooms in unoccupied spaces within 60 feet. These Blooms act on the Grand Matriarch’s initiative and follow its telepathic commands.

Eclipse of Oblivion (Costs 3 Actions). The Grand Matriarch darkens the battlefield with an otherworldly eclipse. The area within 300 feet becomes magical darkness, heavily obscuring all creatures except for the Grand Matriarch and its allies. Creatures in the area take 4d10 necrotic damage at the start of their turn. This effect lasts for 1 minute or until the Grand Matriarch dismisses it as a bonus action.

Unholy Renewal (Costs 2 Actions). The Grand Matriarch releases pulses of necrotic energy to heal itself and its allies. The Grand Matriarch regains 10d10 hit points, and all allied Tenebralis Blooms within 60 feet regain 5d10 hit points.

Additional Mythic Traits in Form

Aura of Endless Devastation. The Grand Matriarch’s aura increases to a 60-foot radius. Creatures that start their turn in the aura take 10d8 necrotic damage and must succeed on a DC 22 Constitution saving throw or have disadvantage on attack rolls, saving throws, and ability checks until the start of their next turn.

Overwhelming Influence. The Grand Matriarch’s telepathic range extends to 500 feet, and its commands have a more profound effect. A creature charmed by the Grand Matriarch cannot act except to defend the Grand Matriarch or attack its allies.