Algoid

Being plants, Algoids employed photosynthesis to generate energy, and a lack of natural light could "starve" one in mere days. An algoid suffering from light deprivation gradually turned entirely black as they died. They are also vulnerable to dry environments and prefer humid and moist ones. Creative use of a Control Water spell can dry out an Algoid and kill it in a few rounds by removing its water. If caught in the area of the spell an Algoid must make a Spell saving throw against CON or loose 3d6 HP. 

Multiattack. The Algoid can make two Slam attacks on its turn or one Mind Blast.

Slam. Melee Attack: +5 to hit, reach 5 ft., one target. Hit: 8(1d10+3) bludgeoning damage.

Mind Blast (1/Day). Spell Attack: +5 to hit, range 120 ft., one target. Hit: 8(2d10+3) psychic damage.

Animate Trees (1/Day). The Algoid magically animates one or two trees of specific types, (mainly those that thrive in water-rich environments such as Cypresses, Water Oaks and Willows) it can see within 60 feet of it. These trees have the same statistics as an Awakened Tree (see the Monster Manual), except they can’t speak. An animated tree acts as an ally of the Algoid. The tree remains animate for 1 day or until it dies, until the Algoid dies or is more than 120 feet from the tree, or until the Algoid takes a bonus action to turn it back into an inanimate tree. The tree then takes root if possible.