Baelnorn

Norn Rejuvenation. If the baelnorn is destroyed, one of its descendants may perform a ritual in which they invite the baelnorn's spirit to assume their body. The descendant remains for a time as a passenger in its former body, and may pass into death at will at any point.

Entangling Aura. A creature that hits the lich with a melee attack must succeed on a DC 21 Strength saving throw or be restrained (escape DC 21) until the end of the lich's next turn as vines burst forth from the nearest surface to entangle it.

Water Walk. The baelnorn can walk across any liquid surface as if it was solid ground.

Legendary Resistance (3/Day). If the baelnorn fails a saving throw, it can choose to succeed instead.

Multiattack. The baelnorn uses its Lignify and makes three attacks with its Wraithblade, one of which it may replace with a use of its Forced Growth or Splinterburst.

Wraithblade. Melee Spell Attack: +13 to hit, reach 5 ft., one creature. Hit: 24 (4d8 + 6) necrotic damage. This attack treats the target as unarmored (An unarmored creature's AC is usually 10 plus its Dexterity modifier).

Lignify (5th Level Spell). One creature within 120 feet the baelnorn can see must succeed on a DC 21 Constitution saving throw or have its flesh begin to turn to wood, gaining the Plant type in addition to its other creature types, plus one additional effect of the baelnorn's choice until cured by Greater Restoration or similar magic:

• The creature's movement speed is reduced by half and it cannot fly.
• The creature can't take bonus actions or reactions.
• The creature gains vulnerability to fire damage.
• The creature takes 11 (2d10) fire damage whenever it deals fire damage.

Forced Growth (Recharge 5-6). The lich causes a tree 15 feet across and up to 100 feet tall to burst forth from the ground at a point it can see within 120 feet. Each creature in the tree's space when it appears and each flying creature within 20 feet of it must make a DC 21 Dexterity saving throw, moving to the nearest unoccupied space on a success. On a failed save, a creature takes 22 (4d10) bludgeoning damage is launched to the tree's top. A creature that failed this save by 5 or fewer may use its react on to grasp a branch and avoid falling.

Splinterburst (Recharges when the baelnorn uses its Forced Growth). One tree the baelnorn can see within 60 feet explodes in a hail of massive splinters. Each creature within 15 feet of the tree must succeed on a DC 21 Dexterity saving throw or take 27 (6d8) piercing damage, or half as much on a success.

Briar Shield. As a reaction to being targeted with an attack, the baelnorn conjures a barrier of thorny vine, gaining 20 temporary hit points that last until the beginning of its next turn.

While it has any of these temporary hit points, a creature that hits it with a melee attack takes 5 piercing damage.

Withering Wail (1/Day, 9th Level Spell). As a reaction to being reduced below 112 hit points, the baelnorn sings out a cruel and keening note. Each plant within 60 feet withers and blackens, and each plant creature in the area must succeed on a DC 21 Constitution saving throw or drop to 0 hit points.

The baelnorn can take 3 legendary actions, choosing from the options below.

Zephyr Step. The baelnorn gains a fly speed equal to its movement speed until the beginning of its next turn and moves up to half its speed.

Hollowheart Harvest. One plant creature or elf the baelnorn can see within 5 feet loses up to 3 unexpended hit dice. The baelnorn regains 1d8 hit points for each hit die lost in this way. 

Deadwood Awakening (Costs 2 Actions). The baelnorn reanimates the wooden portion of a weapon or shield it can see, transforming it into a Vine Blight that acts on the baelnorn's turn under its control.

if the weapon was magical, it transforms back after the vine blight is destroyed, and cannot be affected by this ability again.

Wraithstorm Charge (Costs 2 Actions). The baelnorn moves up to its speed and makes two attacks with its Wraithblade. It may pass through solid objects and creatures with this movement and does not provoke attacks of opportunity.