Corrupted Fire Elemental

One Thousand Flames (Mythic Trait; Recharges after a Short or Long Rest). If The Corrupted Fire Elemental is reduced to 0 hit points, it doesn’t die or fall unconscious. Instead, The Corrupted Fire Elemental erupts into 6 regular fire elementals for ten rounds. At the end of ten rounds, if there are more than 4 regular fire elementals, they congeal back together into one, fully regenerated Corrupted Fire Elemental. If there are not 4 regular fire elementals left, those that remain attempt to flee.

Fire Form. The elemental can move through a space as narrow as 1 inch wide without squeezing. A creature that touches the elemental or hits it with a melee attack while within 5 feet of it takes 5 (1d10) fire damage. In addition, the elemental can enter a hostile creature's space and stop there. The first time it enters a creature's space on a turn, that creature takes 5 (1d10) fire damage and catches fire; until someone takes an action to douse the fire, the creature takes 5 (1d10) fire damage at the start of each of its turns.

Illumination. The elemental sheds bright light in a 30-foot radius and dim light in an additional 30 feet.

Water Susceptibility. For every 5 feet the elemental moves in water, or for every gallon of water splashed on it, it takes 1 cold damage.

Multiattack. The elemental makes two touch attacks and one Fire Bolt attack.

Touch. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 12 (2d8 + 3) fire damage. If the target is a creature or a flammable object, it ignites. Until a creature takes an action to douse the fire, the target takes 5 (1d10) fire damage at the start of each of its turns.

Fire Bolt. Range Spell Attack: +6 to hit, reach 120 ft., one target. Hit: 14 (2d10 + 3) fire damage. If the target is a creature or a flammable object, it ignites. Until a creature takes an action to douse the fire, the target takes 5 (1d10) fire damage at the start of each of its turns.

Fire Ball (Recharge 4-6). Range Spell Attack: DEX SAV, reach 150 ft. 20ft diameter. Hit: 28 (8d6) fire damage, on a failed DEX SAV or half as much on a successful one. If the target is a creature or a flammable object, it ignites. Until a creature takes an action to douse the fire, the target takes 5 (1d10) fire damage at the start of each of its turns.

Wall of Fire (Recharge 5-6). Range Spell Attack: DEX SAV, reach 120ft. Hit: 23 (5d8) fire damage, on a failed DEX SAV or half as much on a successful one.

You create a wall of fire on a solid surface within range. You can make the wall up to 60 feet long, 20 feet high, and 1 foot thick, or a ringed wall up to 20 feet in diameter, 20 feet high, and 1 foot thick. The wall is opaque and lasts for the duration.

When the wall appears, each creature within its area must make a Dexterity saving throw. On a failed save, a creature takes 5d8 fire damage, or half as much damage on a successful save.

One side of the wall, selected by you when you cast this spell, deals 5d8 fire damage to each creature that ends its turn within 10 feet of that side or inside the wall. A creature takes the same damage when it enters the wall for the first time on a turn or ends its turn there. The other side of the wall deals no damage.

Fire Shield (Recharge 3-6). Reaction. Lasts until beginning of next turn.  The warm shield grants you resistance to cold damage. In addition, whenever a creature within 5 feet of you hits you with a melee attack, the shield erupts with flame. The attacker takes 2d8 fire damage from a warm shield.

One Thousand Flames. The Corrupted Fire Elemental erupts into 6 regular fire elementals for ten rounds.

One Flame. At the end of ten rounds, if there are more than 4 regular fire elementals, they congeal back together into one, fully regenerated Corrupted Fire Elemental. If there are not 4 regular fire elementals left, those that remain attempt to flee.