Dark Speech. If the void wishes to speak, it can speak in a deep, haunting voice and expend the Voice of the Great One's bonus action. The Voice of the Great One takes 6 (1d12) psychic damage and all hostile creatures the Voice of the Great One can see take 10 (3d6) psychic damage.

Negative Regeneration. If the Voice of the Great One takes necrotic damage, it instead regains hit points equal to the necrotic damage taken.

Positive Weakness. If the Voice of the Great One takes radiant damage, it must make a DC 18 Constitution Saving Throw or die. 

Rotting Touch. Melee Spell Attack: +6 to hit, reach 5 ft., one target. Hit: 11 (3d4 + 4) necrotic damage, and the target must make a DC 18 Constitution Saving Throw or have their hit point maximum be reduced by the necrotic damage taken. 

Horrific Screech (1/Day). The Voice of the Great One harnesses the void to create an unbearable screech that can be heard out to 300 ft. This triggers other Voices of the Great One in the area to use their action to make a screech as well. All hostile creatures in the area take an amount of psychic damage equal to 3 (1d6) for each Voice of the Great One that can be heard, for a maximum of 105 (30d6), and must make a DC 11 Wisdom Saving Throw or be frightened of all Voices of the Great One for 1 hour.