Unnatural Growth

Doubling shows up all over green's history as a one-time burst: a pump spell resolves, Overrun swings a single turn, an anthem adds a flat number. What this does differently is repeat. The trigger fires at the beginning of each combat, so in a turn where you attack twice (an extra-combat effect, a Combat Celebrant, anything that grants a second combat phase) the doublings compound within that same turn, taking a 2/2 to 4/4 in the first combat and 8/8 in the second before the end-of-turn cleanup resets it. That repeat-trigger structure is what justifies the four green pips: a single-shot enchantment at this size would be laughable, but an every-combat multiplier changes the arithmetic of any race that survives into the next turn. The toughness half matters as much as the power half, because doubled toughness turns damage-based removal and bad blocks into non-events, letting a wide board push through the sweeper window that usually punishes it. And because the trigger reads "each combat," casting it in your precombat main phase pays off the same turn: it fires before you attack rather than sitting dead until the following turn, which spares it the fate of an enchantment deployed purely as a future threat. The cost of all this is the quadruple-green commitment and a reliance on already controlling the board: the multiplier scales with what you have, so it rewards you for winning the position before you ever draw it.