Shadow Stealth. the elemental has an advantage on attack rolls and dexterity (stealth) checks made in dim light or darkness.

Aura of Fear. when a creature takes damage from an attack made by the elemental, the creature must make a DC 10 wisdom saving throw. on a failed save, a creature is frightened until the start of the elemental's next turn. 

Multiattack. The elemental makes two touch attacks.

Touch. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 12 (2d8 + 3) necrotic damage.

Flood of Darkness (recharge 4-6). magical darkness spreads out from the elemental in 10 foot sphere, centered on it. the darkness lasts until the start of the elemental's next turn. The darkness spreads around corners. A creature with darkvision can't see through this darkness, and nonmagical light can't illuminate it, nor can spells of 2nd level or lower illuminate the darkness. the elemental can see through the darkness. 

when a creature enters the darkness for the first time (including when the elemental uses this action) or end's their turn in the darkness, they must make a DC 15 constitution saving throw, taking 10 (3d6) necrotic damage on a failed save.