Aberrant Earth (5e Hazard)
From D&D Wiki
This thick, slimy mud occasionally moves when humanoids are within 60 feet of it, pulsating in their general direction, and vaguely face-shaped formations can be found within it. It covers a 20 square foot patch of ground, though some can be much larger. Any creature that isn't an aberration that starts its turn in aberrant earth or moves into aberrant earth for the first time on its turn must succeed on a DC 15 Wisdom saving throw or take 10 (3d6) psychic damage and be stunned until the end of its next turn. A creature that dies while standing in aberrant earth is absorbed by it, and only a resurrection spell or similar magic can restore it to life. Sometimes, a patch of aberrant earth magically becomes a gibbering mouther of its own accord, though especially large patches might become more than one mouther.