Slam

Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 4 (1d6 + 1) bludgeoning damage. The cackling skeleton has advantage on this attack roll if the target is demoralized.

Mock (Recharge 5-6)

The cackling skeleton mocks the futile efforts of up to three creatures it can see within 30 feet of it that aren't undead or constructs. Each target must make a DC 12 Charisma saving throw, taking 5 (2d4) psychic damage on a failed save, or half as much damage on a successful one. A demoralized target has disadvantage on this saving throw.