Thought Lash

Spend your own library to buy out incoming damage, and pay rent on the privilege every single upkeep. The cumulative upkeep is not a mana tax; it is settled in cards exiled from the top of your deck, so the engine devours the same resource it draws from. Miss a payment and the penalty is absolute: your entire remaining library leaves the game, which in most situations ends matters on the spot. That self-destruct trigger is what earns the prevention effect, which lets you exile a card to stop a single point of incoming damage. The arithmetic is brutal and deliberate: you can fizzle any quantity of burn or combat damage, but each point costs a card, and the upkeep is eating through your deck in parallel. What results is a permanent that reframes decking from a loss condition into a clock you choose to start, then races the opponent's damage against your own shrinking library. It belongs to the Ice Age block's running interest in permanents that convert self-harm into utility, where the question was never whether an effect was strong but how much of yourself you were willing to feed it. Thought Lash poses the most extreme version of that question, and the answer is usually that you cannot afford it for long.