Awakening

A symmetry that wants to be broken. The untap clause fires at the beginning of each upkeep, yours and your opponents', which is the catch the rate is built around: hand it to a deck with no way to exploit the refresh and it just keeps everybody's creatures ready to block and everybody's lands ready to spend. The reward sits entirely in the gap between players who can use untapped permanents at instant speed (mana sinks that fire on the opponents' turns, activated abilities that need open lands, creatures with relevant tap abilities) and players who only get vigilant blockers out of it. The land half is the part that aged into combo currency: an upkeep that refreshes your entire manabase, every turn cycle, is the engine half of a loop rather than a defensive freebie, provided you have an instant-speed outlet to dump the mana into before the symmetry hands it back. That separates it from the untappers green printed later, which trimmed the symmetry that makes this dangerous; Seedborn Muse fires only on opponents' turns and only for your own permanents, the strictly-fairer version of the same idea. The design lineage here is the open-ended symmetric enchantment Wizards has steadily walked back: an effect printed at face value, no "you control" rider, no upkeep cost, trusting the deckbuilder to find the asymmetry. Most of that family ended up as combo enablers rather than the midrange value pieces their text suggests, and green getting handed a leashless repeatable untap is an early, unguarded example of the type.