Green Knight’s Vow (Patreon)

Wondrous item, very rare (requires attunement)

These dark green adamantine and copper bracers are granted to devout warriors of the Infernal Court and are designed to match their army's signature tower shields. While wearing the bracers, you grow a sweeping pair of horns from your forehead if you are not a tiefling. If your attunement to the bracers ends, the horns crack and fall away after 24 hours.

The bracers have a total of 7 charges and regain all expended charges daily at dawn. While wearing them, you can expend 1 or more of their charges to use the following three properties:

"Brace Yourselves!" As a bonus action, you can expend 2 or more charges from the bracers to provide cover to a creature you can see within 30 feet of you. For 2 charges, you summon a large, spectral shield that follows the creature for the duration, providing it with half cover. You can summon one extra shield for each additional charge you expend, targeting a different creature with each one. The shields fade at the end of your next turn.

"Press the Assault!" When you make an opportunity attack, you can expend 1 or more of the bracers' charges to embolden your nearby allies. For each charge you spend, one creature of your choice within 60 feet of you can use its reaction to make one weapon attack. The chosen creatures must be able to see or hear you.

"You Will Burn!" You can expend 1 or more charges from the bracers to cast the hellish rebuke spell (save DC 15) from them. For 1 charge, you cast the 3rd-level version of the spell. You can increase the spell slot level by one for each additional charge you expend. The fire from this spell is a haunting emerald green.

Flaw. The Green Knight's vow makes its wearer tremendously loyal to royalty. While attuned to the bracers, you gain the following flaw: "I will stand by my sovereign leader, no matter what." You or your GM determine who your leader is. In addition, if you are attuned to the bracers for 24 consecutive hours, your commitment to duty drives you to the brink of zealotry. You can't attune to the Red Queen's burden or the Violet King's promise. If you are already attuned to either of them, your attunement to it immediately ends once this effect is extended to you. The first creature you meet who is attuned to either of these weapons becomes your sovereign leader, regardless of who you previously considered it to be. You become charmed by them and obey their commands to the best of your ability. If you find the Red Queen's burden or the Violet King's promise without an owner, you are compelled to protect it with your life until a rightful owner is found. These effects can be removed with a greater restoration spell, but not while you are attuned to the bracers.

When the crowns clashed and the land burned, the green knights stood by the side, watching, unable to act. No one cursed them though, for they knew a knight cannot serve two monarchs.