Underdark Rift

Removal that gambles is a rare thing, and the d10 here is not flavor decoration but the load-bearing element of the whole design. Most bounce-to-library effects tuck a permanent a fixed distance down (top, second, seven cards deep, the bottom), which lets the caster reason cleanly about the tempo they bought. This land instead demands five mana and its own exile, then hands back a random depth between one and ten cards: sometimes it strands a threat for a dozen turns, sometimes it barely stalls a topdeck. That variance is what buys the right to staple an unconditional artifact, creature, or planeswalker answer onto a source that taxes no color and costs nothing to run. The sorcery-speed clause and the exile cost make it a slow, one-shot valve rather than something you fire twice: you pay the ramp, spend the land, and take whatever face the die shows. It belongs to the "removal hidden in a utility land" family, the pieces that ask you to name no color, run no spell, and still hold an out to a resolved bomb. The randomness is precisely what keeps that free tuck from being oppressive; a deterministic version deep enough to matter would be far harder to justify on land that also taps for colorless mana. This is an answer that never occupies a spell slot, its power gated entirely by how much the caster trusts a ten-sided die.