Thalia, Guardian of Thraben

A tax that aggression carries for free. Most resource-denial pieces ask the controlling deck to spend a whole turn on disruption that does nothing in combat; this one staples the tax to a beater that already wants to attack. Making every noncreature spell cost one more does not stop removal or sweepers, it just makes them arrive a beat late, and a beat is often the entire difference when the white deck is racing. The cleverness is in what the tax does not touch: creatures cast around her keep coming at no surcharge, so the deck applying pressure pays nothing while the deck trying to interact pays on every spell. The 2/1 first-strike body is calibrated to the same logic: it pushes damage into open mana and punishes anything with two toughness or less that tries to block, while the single point of toughness means a Lightning Bolt, a Shock, or any x/3-and-up blocker still answers her cleanly. That fragility is the line that keeps the lock from being oppressive: she dies to a wide range of the very removal she just made costlier. She taxes her own controller too, a real bill that disciplined builds pay by leaning on creatures and lands over spells. Her name became shorthand for an entire category that followed: the cheap attacking permanent that bends an opponent's curve out of shape while doing honest work in combat. Stax on a stick, two mana, first strike, and a clock attached.