Abomination

The Unicorn's Charge. If it moves at least 20 feet straight toward a target and then hits it with a horn attack on the same turn, the target takes an extra 9 (2d8) piercing damage. If the target is a creature, it must succeed on a DC 15 Strength saving throw or be knocked prone.

Golom's Immutable Form. It is immune to any spell or effect that would alter its form.

Shark Bite. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 22 (3d10 + 6) piercing damage and the target must make a successful DC 15 Strength saving throw or be thrown 20 feet in a direction of its choice.

Mouher's Blinding Spittle (Recharge 5–6). It spits a chemical glob at a point it can see within 15 feet of it. The glob explodes in a blinding flash of light on impact. Each creature within 5 feet of the flash must succeed on a DC 13 Dexterity saving throw or be blinded until the end of its next turn

Unicorn's Horn. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 8 (1d8 + 4) piercing damage.

Dragon's Wing Attack. It beats its wings. Each creature within 10 feet of the It must succeed on a DC 13 Dexterity saving throw or take 11 (2d6 + 4) bludgeoning damage and be knocked prone. It can then fly up to half its flying speed.

The Blink Dog's Teleport (Recharge 4–6).  It magically teleports, along with any equipment it is wearing or carrying, up to 40 feet to an unoccupied space it can see. Before or after teleporting, the dog can make one bite attack.

Imp's invisibility. It magically turns invisible until it attacks or until its concentration ends (as if concentrating on a spell). Any equipment it wears or carries is invisible with it.

Stone Giant's Rock Catching. If a rock or similar object is hurled at it, it can, with a successful DC 10 Dexterity saving throw, catch the missile and take no bludgeoning damage from it.