You summon a powerful fire elemental, which takes the form of a flaming crown above your head. This crown has no actions and moves with you. It gives you the following benefits. You are immune to fire damage. If you were already immune, you heal half of the damage given when hit by an attack that does fire damage. When you are hit by a melee attack, you may use your reaction to cast Hellish Rebuke at 3rd level without expending a spell slot, even if you do not have it prepared or that attack causes you to drop concentration. Finally, whenever you cast a damaging spell, you may add an extra 2d10 fire damage to it. If the target is immune to fire damage, treat it as a resistance. If it is resistant to fire damage, treat it as if it is not.

The crown disappears if you drop concentration, go unconscious, or dismiss it using an action.