Heirloom Epic

The clever trick here is the payment substitution: the four generic mana in the activation cost can each be swapped for tapping an untapped creature, which turns a repeatable draw engine into something a wide board pays for at almost no mana. The design grafts a convoke-style discount onto card advantage rather than casting cost, and it reframes what your creatures do when they are not attacking. A stalled ground clog, a token swarm, a pile of mana dorks with nothing to ramp into: any of them can be tapped down to refill your hand each turn. The sorcery-speed clause and the tap requirement are what keep the rate fair, since you cannot ambush anyone at instant speed and every creature committed to a card is a creature that cannot block that turn. That trade-off is the whole appeal: board presence versus grip, weighed one draw at a time, rather than inevitability handed over for free. As a one-mana artifact that scales with the number of bodies you can spare, it belongs to a small family of go-wide payoffs that reward horizontal boards not with combat math but with a slow, grinding advantage engine that comes online the moment your creatures have nothing better to do.