Aspect of Wildfire

Molten Skin. Any creature who ends their turn within 10 feet of the aspect takes 16 (3d10) fire damage. Flammable objects within 10 feet of the aspect burst into flames.

Rekindle. If the aspect of fire is at 0 hit points, it regains 10 hit points at the start of its next turn. If the aspect is reduced to 0 hit points by cold damage, or is hit with cold damage while at 0 hit points, rekindle doesn’t function at the start of the aspect’s next turn and the aspect becomes petrified. The aspect can not rekindle for one hour after being petrified. After an hour of being petrified, the aspect will regain all of its hit points and no longer be petrified.

Fuel for the Fire. The aspect of fire doesn’t treat plant life as difficult terrain. Whenever the aspect begins its turn in a space of plant life that provides cover, it burns the plant life away from all spaces it is currently occupying, healing 1d8 hit points for each 5-foot square of such plant life it has consumed. If it heals for 15 or more hitpoints in this way, it flares up, recharging its magma throw action.

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

Multiattack. The aspect makes two molten fist attacks. It may replace one of those attacks with a fiery stomp action, and then it may use its magma throw action if it is available.  

Molten Fist. Melee Weapon Attack: +11 to hit, reach 15 ft., one target. Hit: 28 (4d10 + 6) fire damage.

Fiery Stomp. Each target within a 20ft emanation from the aspect must succeed on a DC 20 Constitution saving throw or take (3d10) fire damage and be knocked prone. Half on a save.

Magma Throw (Recharge 5-6). The aspect hurls a ball of molten rock. Choose a location within 60 feet of the aspect. All creatures within 15 feet of the target location must make a DC 20 Dexterity saving throw. On a failure, a creature takes 33 (6d10) fire damage and is knocked prone. On a success, the creature takes half as much damage.

Spellcasting. The aspect casts one of the following spells, using Wisdom as the spellcasting ability (spell save DC 17, +9 to hit with spell attacks):

At Will: Fire Bolt (level 11 version)
2/Day Each: Fireball (level 5 version), Wall of Fire
1/Day Each: Fire Storm

The aspect 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 aspect regains spent legendary actions at the start of its turn.

Wildfire Surge. Each creature within a 100ft emanation of the aspect must make a DC 20 Dexterity saving throw. On a failure, creatures take (2d10) fire damage. Half damage on a save. 

Channel the Inferno. The aspect can cast a spell using Spellcasting. If the aspect uses this legendary action to cast fire bolt, the aspect may twin that spell, choosing two creatures it can see within range as the targets for the spell.

Ignition. The aspect may empower its next attack by dealing 20 damage to itself. If it does, its next attack is done so with advantage, does an additional (2d10) fire damage, and anyone within 15ft of the target of the attack takes half damage from it. The aspect may only take this legendary action if it has less than half its hit points remaining.