Infernal Crown

Wondrous item, very rare (requires attunement)

Wicked-looking spikes protrude from this circular band of thick black iron. While wearing this crown, you have resistance to fire damage and you always know if a fiend is within 30 feet of you. You can also speak, read, and write Infernal.

Additionally, if you are damaged by a creature within 30 feet of you that you can see, you can use your reaction to cause that creature to be momentarily wreathed in hellfire. The creature must make a DC 15 Dexterity saving throw, taking 1d10 fire damage on a failed save, or half as much damage on a successful one.

You can also summon a devil of challenge rating 4 or lower, which appears in an unoccupied space that you can see within range. The summoning takes 1 minute to complete, and the devil appears in a pillar of hellfire.

The devil is friendly to you and your companions. Roll initiative for the devil, which has its own turns. It obeys any verbal commands that you issue to it (no action required by you). If you don’t issue any commands to the devil, it defends itself from hostile creatures but otherwise takes no actions.

The devil disappears in a puff of acrid smoke when it drops to 0 hit points or after 1 hour elapses. Once you have summoned a devil, you can’t do so again until the next dawn.