Amphibious. The beast can breathe both air and water.
Primal Bond. You can add your proficiency bonus to any ability check or saving throw that the beast makes.
Binding Strike. Melee Weapon Attack: your spell attack modifier to hit, reach 5 ft., one target. Hit: 1d6 + 2 + PB piercing or bludgeoning damage (your choice), and the target is grappled (escape DC equals your spell save DC). Until this grapple ends, the beast can't use this attack on another target.