Mortal Obstinacy

Enchantment removal disguised as a combat aura, and the disguise is the whole design idea. Most one-mana disenchants hand you a clean, immediate answer with nothing asked in return; this one gives you a +1/+1 buff up front and defers the destruction until your creature connects, with the Aura itself as the price of admission. That structure flips the usual math. The pump is free value the turn it lands, but the removal half only fires if the enchanted creature survives blocks and reaches a player, and even then it is optional, so you can leave the boost in place when there is nothing worth destroying. The sacrifice clause is what keeps this from being a strictly better combat enhancer: you spend the Aura's continued presence to buy an enchantment kill, a one-shot exchange folded into a permanent. It rewards a board that is already pressuring the opponent, since the destruction rides on damage you were going to deal anyway, and it goes cold against a stalled or chump-blocked attacker, where the trigger may never come online. As a design it belongs to the lineage of conditional, tempo-positive answers (effects that fold a maybe-relevant clause into a card that does something regardless of whether that clause ever matters), rather than the unconditional disenchants that demand nothing and reward nothing beyond the kill.