Corrupted magma elemental

Magma burrows. The elemental can burrow it self under the ground. The ground that the creature pass creates a blazing ground that if any creature stands there they take 1d8 fire damage at the start of their turn and when they first step into it. 

Corrupted creature. When the creature dies relesease the fire elemental that  are trapped within the creature. The elemental then tries to return to its place before it was corrupted.

Multi attack . The creature may attack twice with its fist 

Fire fist. Melee Weapon Attack: +4 to hit, reach 10 ft., one target. Hit: 20 (3d10 + 10) bludeoning damage. And the target is burned and takes 1d6 fire damage at the start of their turn.

Turbo jump. The elemental jump up to 60ft around them and when it lands all creature within 10ft radius they must make a DC 16 Dexterity saving throw, they take 14 (4d6) fire damage on failed save, and no damage on successful one.

Fire Breath (Recharge 5–6). The elemental exhales fire in a 60-foot cone. Each creature in that area must make a DC 18 Dexterity saving throw, taking 44 (10d8) fire damage on a failed save, or half as much damage on a successful one.