Alligator Snapping Hyrtle

Hold breath: The crocodile can hold its breath for 2 hour.

Stable: The Hyrtle has exceptionally stable footing. Whenever the Hyrtle gets knocked prone, it gets an additional Constitution Saving Throw DC 10 to avoid being knocked prone.

Multiple Heads. The Hyrtle has five heads. While it has more than one head, the Hyrtle has advantage on saving throws against being blinded, charmed, deafend, frightened, stunned, and knocked unconscious.

Whenever the hyrtle takes 10 or more damage in a single turn, one of its heads dies. If all its heads die, the hyrtle dies.

At the end of its turn, it grows two heads for each of its heads that died since its last turn, unless it has taken fire damage since its last turn. The hyrtle regains 5 hit points for each head regrown in this way. This can happen 3 time per day.

Reactive Heads. For each head the hyrtle has beyond one, it gets an extra reaction that can be used only for opportunity attacks.

Wakeful. While the hyrtle sleeps, at least one of its heads is awake.

Straigh Forward: The Hyrtle can't attack creatures behind it.

Softbelly: If the Hyrtle gets knocked prone, it is restrained. To get up on its feet, the Hyrtle has to make a Dex-Save DC10 with disadvantage.

Multiattack: The Hyrtle makes as many bite attacks as it has heads.

Bite: Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 4 (1d6 + 5) piercing damage.

Shelled Up: The Hyrtle can withdraw into its shell as an action. Until it emerges, it gains a +2 bonus to AC, resistence to bludgeoning and slashing damage, has advantage on Strength and Constitution saving throws. While in its shell, its speed is 0 and can’t increase, it has disadvantage on Dexterity saving throws, it can’t take reactions, and the only action it can take is a bonus action to emerge from his shell or the standart action "this will hyrt-le".

This will hyrt-le: Only while shelled up. The hyrtle shoots out its heads in a 5ft cone in front of it. Dealing 1d10 + 3 bludgeoning damage for each head and knocking any creature hit prone, the damage will spread evenly between multiple targets. Creatures can attempt a DEX saving throw DC12 on a success the creature only gets half damage and is not knocked prone. After this action the hyrtle is no longer shelled up.