Bunyip

Amphibious. The Bunyip can breathe air and water.

Legendary Resistance (3/Day). If the Bunyip fails a saving throw, it can choose to succeed instead.

Bog Stealth. While in water or vegetation the Bunyip can take the Hide action as a bonus action and has advantage. It also is not affected by difficult terrain caused by the swamp.

Keen Hearing and Smell. The Bunyip has advantage on Wisdom (Perception) checks that rely on hearing or smell.

Siege Monster. The Bunyip deals double damage to objects and structures.

Frenzy (1 per day). When the Bunyip becomes bloodied, it enters a frenzy, becoming immune against the Stunned, Frightened and Charmed condition, switches its fire resistance and ligthning vulnearability, has advantage on Dex, Str and Con saves but Disadvantage on Wis, Int and Cha saves and resistance against any physical damage. It also gains new traits and all attacks have advantage. The rage ends if it takes less than 50 damage per turn, if that happens the Bunyip suffers three points of exhaustion.

Regeneration. The Bunyip regains 30 hit points at the start of its turn. Only active during frenzy

Bog Blight. The Bunyip is carrier of various diseases, which when mixed becomes a dangerous disease. Each creature hit either by the Bunyips bite attack or fails its save against the bog breath is after one one hour diseased with, which will impede disadvantage on Dexterity, Strength and Wisdom Saving Throws mental ability checks that rely on Wisdom, Charisma and intelligence in addition to having its vision reduced to 30ft, being blind beyond that. This afflicted creature can make a Constitution Saving Throw after each long rest and when the creature succeeds three times it the creature will be cured on a faillure the creature takes (3d10) Poison damage and does not regain hitpoints from the long rest. When a creature succeeds on their third save against the blight, it will become immune to it until it leaves the swamp, after which it takes (1d4+1) weeks for the immunity to wear of. Effects that would normaly remove a disease, does not remove it, but instead allows the creature to repeat it's saving throw.

Bog Poison. Any poison damage caused from the Bunyip ignores resistances and immunity becomes resistance. When the creature is immune to diseases it succeeds automatical on Constutution saving throws against the Bunyip. If the creature is immune agaisnt poison and diseases it is completley immune against it.

Multiattack. The Bunyip makes four attacks: one with its bite, one with its tail and two with its claws.

Bite. Melee Attack Roll: +12, reach 5 ft. Hit: 33 (4d12 + 7) Piercing damage plus snf the target must succeed on a DC 22 Constitution saving throwor take 16 (3d10) Poison damage and after one hour be affected with the bog blight.

Claws. Melee Attack Roll: +12, reach 10 ft. Hit: 20 (3d8 + 7) Slashing damage.

Tail. Melee Weapon Attack:  reach 20ft., 10ft diameter. DC 21 Dex save or take 25 (24 (4d8 + 7) damage and be knocked prone. Success: half damage only

Bog Breath (Recharge 5–6). Constitution Saving Throw: DC 22, each creature in a 60-feet . Failure: 55 (10d10) Poison damage aafter one hour the target is inflicted with bog blight. Success: Half damage only

The Bunyip can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The Bunyip regains spent legendary actions at the start of its turn.

Detect. The Bunyip makes a Wisdom (Perception) check.

Tail Slam. The Bunyip makes a tail attack.

Filthy escape (Costs 2 Actions). The Bunyip emits a cloud of poisonous gas, which also causes leaves, fur from its body and other refuse in the area. The cloud is a 30 ft emanation, which lightly obscures the area. Creatures within the cloud or move into it for the first time on their turn, must succeed on a DC 22 Constitution saving throw or be poisoned until the end of their next turn. At the same time the Bunyip moves up to its speed and takes the hide action.