Decaying Soil

Threshold flips this from a slow liability into a recursion engine, but the upkeep exile fights you the whole way there. The card eats one graveyard card per turn whether you like it or not, and exiling from your yard pushes you away from the seven you need, not toward it. That tension is the design: you have to over-fill the graveyard fast enough that the mandatory exile cannot drain you back below the line, which means leaning on mill, sacrifice, and self-discard to outpace the upkeep tax you pay every turn. Once you cross seven, every nontoken creature dying becomes a one-mana buyback, a Genesis-style loop attached to your sacrifice outlets and chump blockers rather than to a single creature. The payment per recursion meters the engine: you can only loop as fast as your mana allows, and the upkeep exile is quietly clawing back at the same threshold count you spent the game assembling, so the machine is always one bad turn from switching itself off. It is conditional value of a particular early design flavor, when the graveyard was a resource you spent down and refilled rather than a place cards simply went to die, and the cost of access was a steady erosion you had to keep ahead of.