Eldrazi Conscription

The number is the trick. An Aura that grants +10/+10 turns almost any creature into a serious threat given trample, which means the eight mana up front buys you a single combat step that ends the game rather than a permanent advantage. Annihilator 2 is the insurance: even if the enchanted creature gets blocked or chumped, the attack still strips two permanents off the defender, so the swing is punishing whether or not the damage connects. That layered overkill is what makes it a tutor target rather than a hardcast: this is the payoff for Sovereigns of Lost Alara, which fetches it straight onto an attacker mid-combat and sidesteps the prohibitive cost entirely. Hardcast, the Aura suffers the usual two-card-disadvantage problem any big Aura carries, since killing the creature in response eats the enchantment too. Cheated in, it becomes a finisher that asks only that you connect. The annihilator clause is also the cruel part of the design: the defending player chooses what to sacrifice, but losing two permanents per attack erodes their board faster than they can rebuild it, so even a stalled game tilts decisively the moment this resolves on something that can swing.