Vine Lord

Green Regeneration. While in a forest, the vine lord regains 10 hp at the start of its turn if it hast at least 1 hp.

Magic Resistance. The vine lord has advantage on saving throws against spells and other magical effects.

Root Mind. The vine lord and the tendril puppets it has created are connected via a hive mind. The vine lord and its puppets can telepathically communicate with each other, provided the communicating creatures are within 1 mile of each other. In addition, while in a forest, the vine lord can't be surprised.

Vine Seed. A creature infected with a vine lord's vine seed suffers near-constant pain as the seed takes root and spreads tendrils throughout its body. For the first 24 hours after infection, the creature has disadvantage on attack rolls and ability checks, as the pain from the spreading roots distracts it. Then, the seed becomes a disease, devouring the creature from the inside as it grows vines throughout the creature's body. Until the disease is cured, the infected creature can't regain hp, and its hp maximum decreases by 7 (2d6) for every 24 hours that elapse. This reduction lasts until the disease is cured. The creature dies if this disease reduces its hp maximum to 0.

Woodland Walk. Difficult terrain composed of plants doesn't cost the vine lord extra movement. In addition, it can pass through plants without being slowed by them and without taking damage from them if they have thorns, spines, or a similar hazard.

Multiattack. The vine lord makes one Tendril attack and two Thorned Slam attacks.

Tendril. Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 7 (1d4 + 5) slashing damage plus 7 (2d6) poison damage, and the target must succeed on a DC 16 Constitution saving throw or become infected with a vine seed (see the Vine Seed trait).

Thorned Slam. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 14 (2d8 + 5) bludgeoning damage plus 10 (4d4) piercing damage.

Forest Protectors (1/Day). The vine lord magically calls 1d4 awakened trees or tendril puppets, or it calls 1 Plant with a challenge rating of 4 or lower. The called creatures arrive in 1d4 rounds, acting as allies of the vine lord and obeying its spoken commands. The Plants remain for 1 hour, until the vine lord dies, or until the vine lord dismisses them as a bonus action.