Hellish Halo

She shall arrive upon a chariot of steel bearing a talisman of stone, and the fire that once brought life to the world shall reap what it has sown.
You summon a massive halo of flame that surrounds you, igniting the air around your body and infusing you with burning vitality. Whenever a creature enters a space within 10 feet of you for the first time during a turn, or starts their turn there, the target takes 5d10 fire damage. Whenever a creature takes damage from this effect, you gain temporary hit points equal to the damage dealt. You can choose to suppress or reignite this flaming halo as a bonus action.

At Higher Levels: When you cast this spell using a spell slot of 7th level or higher, the fire damage increases by 1d10 per slot level above 6th.