Colossification

A +20/+20 aura is a number chosen for spectacle, not precision: nothing about the game requires twenty rather than ten or five, and that's the point. The design is loud on purpose, a giant-monster set's statement piece that turns any creature into a one-hit kill. The tap clause is what pays for the gift, and it's cleverer than it looks. Because the enter trigger taps the creature it's enchanting, you cannot slap this on a fresh attacker and swing for twenty the same turn: the payoff waits a full turn cycle before that colossus can attack or block. That delay is the entire cost of admission, and it means the twenty-power body is inert on the turn you spend seven mana to make it. The card reads as a build-around finisher and plays as a slow one, which is the tension worth understanding. What sinks its raw efficiency is fragility: seven mana and a card poured into a single creature evaporates to any instant-speed removal, and the tapped creature can't even chump-block in the meantime. Bounce is even worse than a kill spell here, since it returns your investment to hand with the aura gone. It's a haymaker, telegraphed by a full turn of standing still, and haymakers miss. The reward for landing one is that the game usually ends the swing after; the risk is that everything about the setup gives an opponent the window to make sure it never connects.