Dragonbroods' Relic

Most mana rocks that tap creatures for mana rely on a static enchantment effect: Cryptolith Rite and Song of Freyalise turn your whole board into a mana engine every turn. This one is stingier, and the stinginess is deliberate. The first ability taps the artifact itself, so it converts exactly one creature into one mana of any color per turn. That single-shot rate is not a limitation to work around; it is the pace-setter for the card's real purpose. The sacrifice mode demands one mana of every color to fire, which means the fixing half is not incidental value bolted onto a rock. It is the runway to the payoff. Spend the early turns using the artifact to smooth a five-color manabase, and the toll for its own finisher becomes payable right about the time the deck is ready to close. The Reliquary Dragon it produces earns the setup: a 4/4 all-colors flier with lifelink and an enters-the-battlefield trigger that throws 3 damage at anything, whether that means a blocker or a face. The sorcery-speed clamp on the sacrifice keeps it a top-end sink rather than an instant-speed ambush, forcing you to commit on your own turn with the board in view. What results is a single card that describes a full arc: a modest fixer that spends its life feeding a rainbow of spells, then converts itself into the game-ending threat that rainbow was building toward.