Tidal Influence
A clock that ticks to its own schedule, not yours. The tide counter advances every upkeep of yours on a four-counter loop, and the global modifier tracks its position: at exactly one counter every blue creature on the board gets -2/-0, at exactly three every blue creature gets +2/+0, and at four or more the counters all clear, parking the enchantment at zero with no effect until the next upkeep starts the climb again. Crucially, both windows are fully symmetric: the buff and the debuff each read "all blue creatures," so the up phase pumps your opponent's Merfolk alongside yours, and the down phase shrinks theirs alongside yours. The two phases that matter, one and three, sit two turns apart, with a dead zero-counter beat between the reset and the next trough. The legend-style restriction (no casting it while a copy is already in play) is the design discipline keeping the effect from stacking into anything reliable: you get exactly one engine, and it ticks to a cadence you read rather than set. What you are buying is timing, not power. Sequencing aggression around a favorable window any opponent can count just as easily, holding back through the trough and committing through the swell, is the whole game here. It belongs to the Fallen Empires interest in counter-driven, self-regulating permanents that rewarded tracking board state over playing to it, a school that valued bookkeeping and tempo reading more than raw rate.
