Sphinx's Tutelage

The chain is the whole mechanism. Mill two off every draw is a slow clock on its own; the repeat clause is what turns it into a kill condition. Because two nonland cards sharing a color restart the process, the engine feeds on the texture of the opponent's deck rather than the size of your draw step: a heavily mono-colored library detonates in long cascades, while a tightly spread multicolor manabase chokes the chain off early. That variance is the design's defining trait. Against the right deck a single draw can empty a quarter of a library; against a five-color toolbox the same draw barely advances the count. The card pays for that explosiveness by doing nothing to the board: it does not block, does not pressure life totals, and gives the opponent every turn it buys them to find an answer or simply race past it. Pairing it with card-draw is the obvious accelerant, and the loot ability exists to keep the engine fed once your hand runs dry, converting excess mana into fresh draw triggers when no other engine is running. Among the self-contained mill enchantments that win by attrition rather than damage, this one is unusual in caring what the opponent's deck is made of; it rewards a deck willing to build its entire game plan around the opponent's library hitting zero, and punishes an opponent for owning a tidy, single-color manabase.