Eel Hound

Amphibious. The eel hound can breathe air and water.

Pack Tactics. The eel hound has advantage on attack rolls against a creature if at least one of the hound's allies is within 5 feet of the creature and the ally isn't incapacitated.

Bite. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) piercing damage, and the target is grappled (escape DC 14). Until this grapple ends, the creature is restrained, and the hound can't Bite another target.

Slick Spittle. The eel hound covers the ground in a 5-foot square centered on a point it can see within 10 feet of it with its slippery spittle. Each creature standing in that area must succeed on a DC 13 Dexterity saving throw or fall prone. A creature that enters the area or ends its turn there must also succeed on a DC 13 Dexterity saving throw or fall prone. The spittle remains on the ground for 1 minute.

Water Step. The eel hound teleports, along with any equipment it is wearing or carrying, up to 30 feet to an unoccupied space it can see. The origin and destination spaces must contain enough water to partially submerge the hound.