Legendary Resistance (3/Day). If Wyrmbane  fails a saving throw, he can choose to succeed instead.

Aura of Decay. Creatures within 10 feet of Wyrmbane at the start of their turn must succeed on a DC 18 Constitution saving throw or take 10 (3d6) necrotic damage and have their movement halved until the end of their turn.

Undead Nature. Wyrmbane does not need to eat, sleep, or breathe. He is immune to exhaustion.

Corrupted Regeneration. Wyrmbane regains 20 hit points at the start of his turn unless he is in sunlight or radiant damage has been dealt to him since the end of his last turn.

Multiattack. Wyrmbane makes three attacks: two with his Witherclaws and one with his Bite.

Witherclaw. Melee Weapon Attack: +15 to hit, reach 10 ft., one target.
Hit: 19 (3d8 + 8) slashing damage plus 10 (2d8) necrotic damage. 

Bite. Melee Weapon Attack: +15 to hit, reach 5 ft., one target.
Hit: 17 (3d8 + 6) piercing damage plus 10 (3d6) necrotic damage.

Roar of the Mourning Woods (Recharge 5–6). Wyrmbane unleashes a corrupted roar. Each creature within 60 feet that can hear it must succeed on a DC 18 Wisdom saving throw or become frightened and take 27 (6d8) psychic damage. On a success, a creature takes half damage and is not frightened. Creatures already frightened by Wyrmbane instead become paralyzed for 1 round if they fail this save.

Deathsnarl (Recharge 4–6)

Wyrmbane emits a guttural, gurgling snarl that chills the air.

Each creature of his choice within 15 feet must make a DC 20 Wisdom saving throw or become cursed with fear until the end of their next turn. While cursed, the creature cannot take reactions and has disadvantage on attack rolls against Wyrmbane .

If a creature fails this saving throw by 5 or more, they are also frightened for 1 minute (save ends at end of each of their turns).

Withering Rebuke (1/Turn)

When a creature within 10 feet of Wyrmbane  hits him with a melee attack, he can lash out with necrotic rage.

The attacker must make a DC 20 Constitution saving throw. On a failure, they take 22 (4d10) necrotic damage, and their Strength score is reduced by 1d4 (to a minimum of 1) for 1 minute. The target may repeat the save at the end of each of its turns, ending the effect on a success.

Wyrmbane 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. He regains spent legendary actions at the start of his turn.

• Claw Attack (Costs 1). Wyrmbane makes one Witherclaw attack.

• Shadow Step (Costs 2).  Wyrmbane teleports 30 feet in any direction.  

• Necrotic Bloom (Costs 3). A 10-foot radius area of ground within 60 feet erupts in black fungal growth. Creatures in the area must succeed on a DC 18 Strength saving throw or be restrained and take 18 (4d8) necrotic damage. The terrain becomes difficult.

Mythic Trait: Broken Soul Unleashed

When Wyrmbane is reduced to 0 hit points for the first time, instead of dying, he lets out a soul-rending roar that echoes across the woods. His corpse erupts in a blast of necrotic energy, and from the ruin of his body rises his true form:

a Dire Werebear, bloated with death magic, shadow tendrils writhing from his back and maw splitting wider than nature should allow.

• Wyrmbane hit points are fully restored (350 HP).

• His type becomes Undead/Shapechanger.

• He gains vulnerability to radiant damage

• His Aura of Decay becomes Aura of Unmaking, and all damage it deals becomes force.

• He gains new abilities, including shadowy tendril attacks that grapple, restrain, and consume life.

🧟‍♂️ Wyrmbane , Aspect of the Shadowed Maw

Gargantuan Undead (Shapechanger), Chaotic Evil

HP: 550
Speed: 60 ft., climb 40 ft., shadow step (see below)
Aura of Unmaking: All creatures within 30 ft. take 13 (3d8) force damage at the start of their turns (no save), and magical healing is halved.

🧿 New Trait: Tendrils of the Void

At the start of each of his turns, 4 shadowy tendrils erupt from Wyrmbane body. Each tendril can target one creature within 30 ft.

• Tendril Lash. +15 to hit, reach 30 ft., one creature. Hit: 14 (2d8 + 5) necrotic damage and the creature must succeed on a DC 21 Strength saving throw or be grappled (escape DC 21).

• While grappled, a creature is restrained and takes 18 (4d8) necrotic damage at the start of each of its turns.

• A creature that dies while grappled is instantly turned into a shadowspawn (use Shadow stat block, immune to sunlight weakness).

Tendrils can be destroyed (AC 18, 30 HP each), but Wyrmbane regrows them at the start of his turn unless in sunlight.

🧭 New Bonus Action: Shadowstep (Recharge 4–6)

Wyrmbane  teleports up to 60 feet to a shadow he can see. Immediately after, up to 2 tendrils lash out at targets within range. If both tendrils hit the same creature, that creature is dragged 30 feet toward Wyrmbane and knocked prone.

New Reaction: Devour the Light

When a creature within 10 feet casts a healing spell or radiant spell, Wyrmbane can force them to make a DC 20 Constitution saving throw. On a failure, the spell fails and is absorbed by Wyrmbane , who regains hit points equal to the spell’s level × 5.

Mythic Legendary Action

• Tendril Maelstrom (Costs 3). All creatures grappled by Wyrmbane tendrils are hurled 30 feet in a direction of his choice and take 27 (6d8) force damage. Each target must also succeed on a DC 20 Dex save or be knocked unconscious for 1 minute (save ends at end of each turn).