Underground Sight. The Infester can use any spell that requires vision on the target while underground as long as they are within the Infester's tremor sense range.

Infectious Acid. any humanoid creature that is killed by the Infester's acid will get up on their next turn as an Infested Humanoid, they will remain active for 1 hour at which point they will explode.

Telepathy. The Infester can speak into the mind of any sentient creature within 60ft that knows a language and can understand any spoken language of a creature within 60ft of it.

Spellcasting. The Infester is a 8th-level spellcaster. Its spellcasting ability is Charisma (spell save DC 14, +6 to hit with spell attacks). The Infester has following Sorcerer spells prepared:

Cantrips (at will): Acid Splash, Infestation, Message, Mind Sliver

1st level (4 slots): Acid Stream, Ray of Sickness, Earth Tremor, Charm Person

2nd level (3 slots): Crown of Madness, Web, Suggestion

3rd level (3 slots): Animate Dead, Enemies Abound, Hypnotic Pattern

4th level (2 slots): Confusion, Vitriolic Sphere

Slam. Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 3 (1d8-1) Bludgeoning damage. 

Acidic Escape. When the Infester is hit by a melee attack it expel's a cloud of acidic gas turns invisible until the start of it's next turn and shift six squares, the Infester can only do this once per short rest.