Amogus

Sus. The Amogus emanates a psychic pulse at all times, that causes any creature within 60 ft. of it to have disadvantage on Wisdom saving throws. 

Multiattack. The Amogus makes 7 attacks: 1 with its tongue, 2 with its psychic wave, and 4 with its Imposter's Glare.

Tongue. Melee Weapon Attack: +5 to hit, reach 10 ft., 1 target. Hit: 16 (3d6 + 6) piercing damage.

Psychic Wave. Ranged Weapon Attack: +10 to hit, range 20/60 ft., 1 target. Hit: 14 (4d4 + 4) psychic damage.

Imposter's Glare. Ranged Weapon Attack: +10 to hit, range 15/30 ft., 1 target. Hit: 6 (1d4 + 2) sussy damage.

Self Report. When the Amogus kills or incapacitates a creature, it can use its reaction once per turn to emit a psychic explosion, causing all creatures within 10 ft. of it to make a DC 15 Wisdom saving throw, taking 7d4 psychic damage on a failed save, or half as much damage on a successful one.

At the end of the Amogus's turn, it can take up to 2 Legendary Actions. It has 6 Legendary Actions. It regains 1 Legendary Action at the start of its turn.

Vote (Costs 1 Action). The Amogus creates a subtle psychic effect that describes a creature it can see within 60 ft. of it as suspicious, causing any creature that hears the description to gain disadvantage on Wisdom (perception) checks unrelated to that creature, and advantage on Wisdom (perception) checks that relate to that creature (e.g. seeing that creature attempt to sneak or pick a lock.) This effect lasts for 5 minutes, or until the Amogus dies.

Imposter (Costs 3 Actions). The Amogus uses an illusion to make itself appear to be a creature it has seen in the last 24 hours. Creatures that have a strong positive or negative relationship with the imitated creature take 2d6 psychic damage when they make a successful attack on the Amogus. Creatures who didn't see the Amogus when it created the illusion can't tell it is an illusion unless and Identify spell or similar magic is used.

Vent (Costs 2 Actions). The Amogus burrows up to 30 ft. through solid metal. It can't burrow through other materials.