Aleksipug

Charge. If the aleksipug moves at least 20 feet straight toward a creature and then hits it with a gore attack on the same turn, the target takes an extra 19 (3d12) piercing damage. 

Grasping Tentacles. The aleksipug can have up to four tentacles at a time. Each tentacle can be attacked (AC 15; 17 hit points; immunity to poison and psychic damage). Destroying a tentacle deals no damage to the aleksipug, which can regrow all tentacles after a short or long rest. A tendril can also be broken if a creature takes an action and succeeds on a DC 18 Strength check against it.

Magic Weapons. The aleksipug's weapon attacks are magical.

Secure Memory. The aleksipug is immune to the waters of the River Styx as well as any effect that would steal or modify its memories or detect or read its thoughts.

Multiattack. The aleksipug makes three attacks. One with its gore and two with its hooks. It can replace one hook attack with a tentacle attack.

Gore. Melee Weapon Attack: +13 to hit, reach 5 ft., one target. Hit: 21 (2d12 + 8) piercing damage. 

Hook. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit: 17 (2d8 + 8) piercing damage.

Tentacle. Melee Weapon Attack: +13 to hit, reach 5 ft., one target. Hit: 15 (2d6 + 8) bludgeoning damage, and the target is grappled if it is Medium or smaller (escape DC 18). The aleksipug has four tentacles, each of which can grapple one creature.

Spit Acid (recharge 5-6). The aleksipug spits a glob of acid at a point it can see within 120 feet of itself that then explodes in a 20 foot radius sphere. Each creature in the sphere must make a DC 20 Dexterity saving throw, taking 55 (10d10) acid damage on a failed save, or half as much damage on a successful one.