Copernus

Beast Transformation. It is able to transform into any beast in existence. Preferably he turns into a ferret.

Action Name. Destroy. It is a 10% plus the user's dex bonus o an instant kill.

Claw Strike. Melee Weapon Attack: +10 to hit, reach 5 ft., 1 target. Hit: 2 (1d8 + 10) [piercing] damage. 

Wild Flare. RangedWeapon Attack: +15 to hit, range 100/1000 ft., 1 target. Hit: 3 (5d6 + 10) [fire] damage.

Wild Step, As a bonus action, he is able to cover himself in wild fire and teleport to any point within the vision for 100 feet.

Combust. When he is hit, he will combust into a green flame called wild flame. He will be unharmed but the attacker must make a dex save of 18 or he will take 10d12 fire damage.

When he is at half hp he will be able to use this until he is above half hp. >250

Bombastic Reaction (Costs 1 Action). When he is below half hp <250, he will practically explode into a wildfire. In a 50-foot diameter, it will be a bubble full of wildfire, with him at the epicenter of it. When he uses the ability, everyone must make a dex saving throw of 20 to dodge the explosion. On failure, they take 5d10 piercing damage and 5d10 fire damage. After that, if anyone does not escape the bubble by the end of their turn they must make a con saving throw of 15 or take 2d10 fire damage. On succession, you take half the damage. This bubble will last for 3 of the monster's moves.

He can only do it once per long rest.

Wendigo Riser(requires 1 minute of concentration). Once per long rest Copernus is able to conjure up wendigos from the ground. Every minute of concentration conjures up 1 wendigo.