Kinnan, Bonder Prodigy

Mana doublers usually live on artifacts you have to protect and untap, but the triggered half of this design moves the doubling onto the creature and reframes what counts as a mana rock: whenever you tap a nonland permanent for mana, every dork, every Mox, every rock in play now generates an extra mana of whatever type it made. That single clause is why the card became shorthand for a specific abuse pattern. Basalt Monolith and its kin flip from "makes three" to "makes four," which is enough to close infinite loops that a plain untap engine cannot reach, and the design deliberately excludes lands from the trigger so the payoff lives entirely in nonland mana sources. The activated ability is the honest tax that pays for all of it: a seven-mana cheat-a-non-Human-creature-into-play toolbox that reads as an afterthought until the mana it enables makes activating it trivial, at which point it becomes a repeatable dig for the biggest body in the deck. What makes the whole package sing is the anti-synergy baked into the exclusion clauses: it rewards artifact mana over land mana, and it hunts for non-Human creatures despite being a Human itself, so the deckbuilding follows a narrow but sharp channel. It is the rare two-drop legend whose ceiling is measured not in combat but in how fast the mana it multiplies can be converted into a game-ending line.