Wondrous Item, rare (requires attunement)
The Backbrace of Sabboth is a dragonhide armorpiece that fits around the spine and grants the Elder Dragon's favor.
When you deal damage from a spell or weapon attack, you may add force damage equal to your Armor Class at a cost. You gain a point of exhaustion, and this feature cannot be used until next dawn.
The Backbrace is also linked to the Elder Dragon, and they can communicate with the wielder.