Vaelkir, the Verdant Fiend

Fiendish Vitality:
Vaelkir regains 10 hit points at the start of its turn if it has at least 1 hit point.

Magic Resistance:
Vaelkir has advantage on saving throws against spells and magical effects.

Corrupted Nature:
Vaelkir’s presence corrupts the land around it. Non-fiend creatures within 30 feet have disadvantage on Wisdom (Survival) and Intelligence (Nature) checks.

Shapechanger:
Vaelkir can use its action to transform into a large, fiendish tree or back into its true form. While in its tree form:

• Its movement speed becomes 0.
• It gains resistance to bludgeoning, piercing, and slashing damage from nonmagical weapons.
• It can’t take actions other than casting spells.

Vaelkir is a 9th-level spellcaster. Its spellcasting ability is Wisdom (spell save DC 16, +8 to hit with spell attacks). It has the following druid spells prepared:

• Cantrips (at will): Druidcraft, Thorn Whip, Produce Flame
• 1st Level (4 slots): Entangle, Faerie Fire, Thunderwave
• 2nd Level (3 slots): Barkskin, Moonbeam
• 3rd Level (3 slots): Call Lightning, Plant Growth
• 4th Level (3 slots): Blight, Wall of Fire
• 5th Level (2 slots): Insect Plague

Multiattack:
Vaelkir makes two attacks with its claws or uses its Fiendish Strike and casts a spell.

Claw: Melee Weapon Attack: +6 to hit, reach 5 ft., one target.
Hit: 12 (2d8 + 3) slashing damage.

Fiendish Strike (Recharge 5-6):
Vaelkir channels fiendish energy into a strike, forcing a target within 10 feet to make a DC 16 Dexterity saving throw. On a failed save, the target takes 27 (6d8) fire or poison damage (Vaelkir’s choice). On a success, the target takes half damage.

Nature’s Retribution (Recharge 5-6):
Vaelkir summons vines and roots infused with infernal energy. Each creature within 20 feet must succeed on a DC 16 Strength saving throw or be restrained for 1 minute. Restrained creatures take 9 (2d8) poison damage at the start of their turns. A restrained creature can use its action to make a Strength (Athletics) check against the DC to escape.

Wrathful Counter:
When Vaelkir takes damage from a ranged attack, it can summon a vine to lash out at the attacker. The creature must succeed on a DC 16 Dexterity saving throw or take 10 (3d6) piercing damage and be pulled 10 feet closer to Vaelkir.

Vaelkir can take up to 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.

• Vine Snap (Costs 1 Action): A creature within 30 feet must succeed on a DC 16 Strength saving throw or be knocked prone.
• Infernal Flames (Costs 2 Actions): Vaelkir creates a burst of flames in a 10-foot radius centered on a point it can see within 60 feet. Each creature in that area takes 14 (4d6) fire damage.
• Fiendish Renewal (Costs 3 Actions): Vaelkir regains 20 hit points.