Blauncher

False Appearance. While the Blauncher remains motionless, it is indistinguishable from a normal dead tree.

Siege Monster. The Blauncher deals double damage to objects and structures.

Innate spellcasting. The Blauncher's innate spellcasting ability is Wisdom (spell save DC 16). It can innately cast the following spells, requiring no components. Spells can only target creatures the Blauncher has grappled.

At will: Ensnaring Strike, Chill Touch, 

3/day each: Wither and Bloom, Blight 

Multiattack. The Blauncher makes two root attacks, each can be replaced with a Thorn attack.

Root. Melee Weapon Attack: +12 to hit, reach 15 ft., one target. Hit: 16 (2d6 + 7) bludgeoning damage and the target is grappled (Escape DC 22). If the target is size Medium or smaller, the target is also restrained. The Blauncher can grapple up to two creatures with its roots, if a creature is grappled this way, the Blauncher can only make root attacks at that creature with that root.

Thorn. Ranged Weapon Attack: +12 to hit, range 30/90 ft., one target. Hit: 11 (1d6 + 7) piercing damage, plus 6 (1d4+3) necrotic damage.
Any Thorn attack that misses, spawns 2 (1d4) Twig Blight within 5ft of the target, once this feature has spawned 12 Twig Blights, it cannot spawn a Twig Blight again for 24 hours.

Blight breath. (Recharge 5-6): The Blauncher exhales a 20-foot-radius sphere of toxic, black-green fog, centered on a point within 20ft. The fog spreads around corners. It lasts for 1 minute or until dispersed by a strong wind. The area is heavily obscured.

When a creature enters the spell's area for the first time on a turn or starts its turn there, that creature must make a Constitution saving throw. The creature takes 22 (5d8) necrotic damage on a failed save, or half as much damage on a successful one. 

The fog moves 10 feet at the start of each of the Blauncher's turns in the same direction it was emitted. Expanding to fill the clouds radius as it passes over gaps or bumps in the ground, and flowing around corners.

Sap: The Blauncher saps the life from a grappled target which must make a DC20 Constitution saving throw or take 10 (3d6) necrotic damage. The Blauncher regains hitpoints equal to half the necrotic damage dealt, and the target's hit point maximum is reduced by the same amount. If this effect reduces a creature's hit point maximum to 0, the creature dies. This reduction to a creature's hit point maximum lasts until the creature finishes a long rest or until it is affected by a greater restoration spell.