Xenowhale

Retract Tongue. If a creature is grappled by the xenowhale's tongue, the xenowhale may take a bonus action to retract its tongue. The target must succeed a DC 16 Strength saving throw or it is pulled to within 5 ft. of the xenowhale and remains grappled. If the target succeeds, it is released from the grapple. 

Trampling Charge. If the xenowhale moves at least 20 feet straight toward a creature and then hits it with a ram attack on the same turn, that target must succeed on a DC 15 Strength saving throw or be knocked prone. If the target is prone, the xenowhale can make one stomp attack against it as a bonus action.

Amphibious. The xenowhale can breathe air and water.

Echolocation. The xenowhale can't use its blindsight while deafened.

Keen Hearing. The xenowhale has advantage on Wisdom (Perception) checks that rely on hearing.

Tongue. Melee Weapon Attack: +5 to hit, reach 25 ft., one target. Hit: 10 (2d6 + 3) bludgeoning damage. If the target is a creature, it is grappled (escape DC 16). Until this grapple ends, the target is restrained, and the xenowhale can't use its tongue on another target. The tongue is considered in range to creatures along its path while it is out.

Bite. Melee Weapon Attack: +10 to hit (+15 if grappled by xenowhale) , reach 5 ft., one target. Hit: 26 (5d8 + 4) piercing damage.

Ram. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 24 (4d8 + 6) bludgeoning damage.

Stomp. Melee Weapon Attack: +10 to hit, reach 5 ft., one prone creature. Hit: 29 (4d10 + 7) bludgeoning damage.