Legendary Resistance (3/Day).

If the lich fails a saving throw, it can choose to succeed instead.

Rejuvenation.

If it has a phylactery, a destroyed lich gains a new body in 1d10 days, regaining all its hit points and becoming active again. The new body appears within 5 feet of the phylactery.

Actions

Multiattack.

The lich makes four attacks.

Poisonous Touch.

Melee Weapon Attack: +9 to hit, reach 10 ft., one creature. Hit: 17 (5d6) poison damage, and the target must succeed on a DC 19 Constitution saving throw or be poisoned for 1 minute. The target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Wither.

Ranged Spell Attack: +9 to hit, range 60 ft., one target. Hit: 14 (4d6) necrotic damage.

Fire Storm (7th-Level Spell; 1/Day).

The lich fills up to ten 10-foot cubes with fire. Every cube must be within 150 feet of the lich and occupy a space the lich can see, and each cube must have at least one face adjacent to the face of another cube. Each creature in the area must make a DC 19 Dexterity saving throw, taking 38 (7d10) fire damage on a failed save, or half as much damage on a successful one. The fire ignites flammable objects in the area that aren't being worn or carried. If the lich chooses, plant life in the area is unaffected by the spell.

Spellcasting.

The lich casts one of the following spells using Wisdom as the spellcasting ability (save DC 19):

At will: druidcraft
3/day each: detect magic, fog cloud, pass without trace
1/day each: antilife shell, dispel magic, speak with plants, transport via plants

Legendary Actions

The lichen lich 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 lichen lich regains spent legendary actions at the start of its turn.

Attack. The lich makes an attack.
Poison Prick (Cost 2 Actions). The lich targets one poisoned creature it can see within 30 feet of it. The target must succeed on a DC 19 Constitution saving throw or fall unconscious until the poisoned condition ends on it.
Sap Life (Costs 2 Actions). The lich targets one creature it can see within 30 feet of it. The target must succeed on a DC 19 Constitution saving throw or take 11 (2d10) necrotic damage. The lich regains a number of hit points equal to the amount of damage that the creature takes.

Lair Actions

On initiative count 20 (losing initiative ties), the lichen lich can take a lair action to cause one of the following effects:

Poisonous spores fill a 10-foot cube that the lich can see within 120 feet of it. Any creature that enters the cloud for the first time on a turn or starts its turn there must succeed on a DC 19 Constitution saving throw or be poisoned until the end of its next turn. The cloud lasts for 1 minute or until it is dispersed by a strong wind.
The lich commands the might of its diseased grove, creating a shambling mound. The shambling mound appears in an unoccupied space within 30 feet of the lich, acts on its own initiative count, and obeys the lich's commands. The shambling mound dies after 1 hour or when the lich uses this lair action again.
Rotten roots and vines magically erupt in a 20-foot radius centered on a point on the ground that the lich can see within 120 feet of it. The lich is unaffected by the roots and vines. For all other creatures, the area becomes difficult terrain, and each creature in the area must succeed on a DC 19 Strength saving throw or be restrained by the roots. As an action, a creature can try to free itself or another creature within its reach, doing so with a successful DC 19 Strength (Athletics) check. The roots and vines wilt away when the lich uses this lair action again or when the lich dies.

Lichen Lich