Might of Alara

The arithmetic is the whole proposition, and it runs the cost curve backwards. A combat trick normally charges more for a bigger swing; here the size is paid in advance, baked into how many basic land types your manabase is willing to carry rather than the green mana you spend at instant speed. One basic land type makes this a +1/+1 for one mana, an embarrassing trade; three types match Giant Growth; the full five-type spread cashes out as +5/+5 for a single green, which is blowout territory no other one-mana green trick can reach. The friction is self-imposed and steep, because squeezing the spell to its ceiling pulls your lands toward a greedy mix of all five basics (or duals carrying multiple types), the opposite of what a lands-light green deck wants. That makes the card legible: it is built for a deck already touching every color, where domain is a resource you are accumulating for its own sake and this simply spends it. Domain as a keyword exists to gate power behind a deckbuilding promise, paying out only to players who kept it, and few cards in the cycle express that bargain as bluntly as a one-mana pump whose payout swings from negligible to game-ending entirely on the lands you chose months before the combat step.