Lake of the Dead

The original ritual-land, and a study in paying twice. Most accelerants charge one cost up front; this one taxes you at the door (sacrifice a Swamp just to arrive), then offers an activated ability that eats another Swamp to turn a single tap into four black mana. That second cost is the whole balancing act: every burst of acceleration shrinks the land base that fed it, so the explosive turn and the long game pull in opposite directions. The math is the appeal. Tap it and crack a Swamp and you produce mana no basic can match, but each activation thins your ability to do it again, which makes this a one-shot detonator rather than a repeatable engine. The entry clause complicates things further: it is a replacement effect, so it does not sit on the stack but instead modifies how the land enters, costing you a Swamp the moment you try to play it. With no Swamp to feed it, the land never arrives at all and goes straight to the graveyard. It belongs to a small Alliances lineage of lands that demanded land sacrifices in exchange for outsized effects, a design space Wizards has largely retired because the payoff (sudden, color-locked burst acceleration) is hard to balance against the steady, attritional cost of feeding it.