Withercrown

The trick is what it refuses to do: it does not kill the creature. Most cheap black removal at this rate wants to send the thing to the graveyard, but this instead installs a slow bleed on top of the target and hands the choice back to the opponent. Zeroing base power neuters an attacker while leaving toughness intact, so the creature stays on the battlefield as a body that can chump-block, while the upkeep clause forces a real decision every turn: eat a point of life or sacrifice the thing. The complication is that the decision belongs entirely to the opponent, and the sacrifice clause the Aura grants triggers only on their upkeep. Nothing here stops them from feeding the enchanted creature to their own sacrifice outlet at instant speed for profit, wringing a death trigger out of what you meant to neutralize. So the Aura does not lock a creature down; it converts it into a liability that ticks against its controller's life if they leave it alone. The design cost is that it is an Aura, carrying the two-for-one risk that answering a creature with an enchantment always has: bounce or flicker the creature and the removal evaporates. What you buy for that fragility is a soft kill that keeps pressuring the opponent's life total while it neutralizes, rather than a hard answer that resolves and stops. It is removal built to punish patience, priced for the aggressive black decks that want the board clear and the clock running at once.