Crosis's Catacombs

The Lairs are an early-era attempt to sell trustworthy three-color mana before fixing had a deep vocabulary: a land that costs nothing in mana but charges its rent in tempo, bouncing a land you already played back to your hand. Crucially, it enters untapped and is immediately usable, which is exactly what separates the Lairs from later bounce lands that come in tapped. What you are buying is not ramp but a swap: one available land converted into a future land drop plus three colors of fixing, with a full turn of development as the cost. The sacrifice clause is the enforcement mechanism: drop it with no land to return and it simply dies. The cleverness hides in the non-Lair restriction, which stops you from chaining Lairs into each other and recouping nothing, so each one demands a real land as collateral. In a Grixis deck of the period, that math could pay off when fixing three colors honestly was genuinely hard. The trade has aged poorly: every fixing innovation since (painlands that hurt instead of stall, fastlands that arrive untapped early, the triomes that fetch) attacks the same problem without forfeiting a turn. The Catacombs survives as a karoo for the rare deck that wants to abuse land-bounce triggers, and as a record of how expensive reliable three-color mana once was.