Wembe

Harmless Appearance. Wembe appears to be a normal fern or palm plant with no characteristics that stand out. Only upon close examination (generally only achievable by getting within attacking range) can one notice the thin, purple edges of its leaves

Swarm. Wembe grows in large patches of connected plants and will attack multiple targets all at once. Make a melee weapon attack roll for each target. Each plant has its own HP.

Coordinated Sneak Attack. Wembe will wait until multiple targets are within range and will roll initiative with advantage unless the target is explicitly investigating the plant. 

Leaf Attack. Melee Weapon Attack: +4 to hit, reach 5 ft., all targets within range. Hit: 8 (4d6 + 3) piercing damage.

Trapped Attack. Upon a successful hit, the target must succeed a STR saving throw of 8 to break free from the wembe's grasp. A failed save will result in the target being held until their next turn at which point they will be able to attempt another STR saving throw as an action. Every failed attempt will cause an extra Hit: 4 (2d6) piecing damage and prohibit movement. The wembe will attack trapped targets with advantage on its next turn.