Bunyip

Hold Breath. The Bunyip can hold it's breath for up to an hour while it is on land

Camouflage. The Bunyip has advantage on Stealth checks made while in a swamp, lake, or pond.

Ambusher. The Bunyip has advantage on attack rolls made against a surprised target

Matted Fur. If a creature makes a successful melee attack from within 5 ft of the Bunyip, the creature is considered grappled, and must make an Athletics check of a DC 13 to successfully escape.

Wounded Fury. While the Bunyip has 10 or fewer hit points, it has advantage on attack rolls. In addition, it deals an additional 7 (2d6) damage to any target it hits with a melee attack. 

Bite: Melee weapon attack: +5 to hit, reach 5ft, one target. Hit: 8 (2d4+3) piercing damage. On a critical hit, the target must succeed a DC 11 Strength or Dexterity saving throw or have a limb severed (Up to DM's discretion)

Slam: Melee weapon attack: +5 to hit, reach 5ft, one target. Hit: 7 (1d8+3) bludgeoning damage. 

Terrifying Roar {4-6}: Each creature within 30ft of the Bunyip that can hear must make a DC 13 Wisdom saving throw. On a failure, they take 2d6 psychic damage and are frightened for 1 minute, and are able to repeat the save at the end of their following turns. On a successful saving throw, a creature is immune to this effect for 24 hours.