Epic Proportions

The flash is the entire reason this is more than a top-heavy Aura. Six mana for +5/+5 and trample is a steep rate at sorcery speed, where you'd expect the bonus to read as a finisher on an already-resolved board. Played at instant speed, the math changes: it ambushes a blocker who walked into a fair fight, turns a chump-block into a fatal one, or saves a creature from removal by inflating it out of burn range mid-combat. The trample matters here too; the point of dropping +5/+5 on an attacker after blocks are declared is to push damage past the body that was supposed to stop it, and trample guarantees the overflow lands. Auras carry the structural risk that defines them: kill the creature in response and the whole investment evaporates, so the flash also functions as a way to wait until the target is least exposed rather than committing it on your main phase. It belongs to the small family of combat-trick enchantments that ask you to hold up mana and threaten, a green answer to the white and blue instants that traditionally own the post-blocks decision window. The cost keeps it honest: at six mana the surprise has to win the game it interrupts, because you rarely get a second one.