Armor Class 14 (natural armor)
Hit Points 93 (11d8 + 44)
Speed 20 ft., swim 40 ft.
Skills Perception +4
Damage Resistances psychic
Senses darkvision 120 ft., passive Perception 14
Languages Common, Deep Speech, telepathy 60 ft.
Challenge 5
Abolethic Vassal. The skum is permanently charmed by its aboleth master.
Amphibious. The skum can breathe air and water.
Psychic Conditioning. The skum is immune to the frightened and charmed conditions unless they are from effects created by an aboleth.
Water Dependency. The skum takes 6 (1d12) acid damage every 10 minutes it goes without exposure to water.
Multiattack. The skum makes three attacks: two with its trident and one with its Mind-Breaking Touch.
Trident. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 7 (1d6 + 4) piercing damage.
Mind-Breaking Touch. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 18 (4d8) psychic damage, and the target has disadvantage on Wisdom saving throws until the end of the skum's next turn.
GoS, p. 254