Brass's Tunnel-Grinder // Tecutlan, the Searing Rift

Rummaging on the front asks only for a graveyard-feeding shell to pay off, but the real design tension lives in the transform clause. Three bore counters, one per turn you descended, means the flip is a three-turn commitment gated entirely on filling your own graveyard: a self-mill deck earns Tecutlan on schedule, while a deck that only occasionally trades permanents may never see the back face. That patience buys the payoff, because Tecutlan is not a modest land. Every permanent spell cast using mana it produced triggers discover equal to that spell's mana value, and the key constraint is that the spells discover hands you for free do not tap Tecutlan and therefore do not chain back into it. The engine is one tap, one discover, sized to what you paid for: the ceiling belongs to the deck willing to run its Tecutlan mana into the fattest permanents it can, which inverts the usual math where cheaper is better. Here expensive is the point. The card is really two payoffs stitched together by a counter: a smoothing effect for the early game and a snowballing mana-into-value engine for the late one, with the bridge between them being how aggressively you are willing to grind your own library down to earn the flip.