Ebon Stronghold

Black's entry in the cycle of five "sacrifice lands" that traded the convenience of an untapped source for a one-time burst, and the design is built entirely around deferred payment. The tempo cost lands up front, since the card enters tapped and offers no mana on the turn it shows up. The second mode trades a permanent for acceleration, so the card is really a question of timing: when do you stop drawing on the resource and cash it in for one big black-heavy turn? That makes it a source that holds a stored payoff rather than a repeatable engine, because the doubled black is a finishing surge, not a sustained stream. The sacrifice clause quietly feeds anything that rewards lands hitting the graveyard or black mana arriving in pairs, which is the niche these have always occupied. Where it earns its keep is in grindy, sacrifice-leaning shells that barely notice the tapped drawback; an aggressive deck cannot stomach a land that sits idle on arrival, but a slow black build treats the entry tax as a rounding error against the payoff of cracking it for a doubled black turn later.