Tidecaller Mentor

Fill the graveyard past seven and this Rat's arrival becomes a bounce aimed at almost anything on the board: an opposing threat set back a full cast, one of your own enters-the-battlefield creatures reset for a second trigger, an equipment peeled off its wearer, a planeswalker sent home before it ultimates. Against a token the return is terminal, since a token bounced to hand ceases to exist; against a real card it is only a tempo tax, buying a turn rather than an answer. The intervening "if" clause is the balancing line. Below seven cards the ability never checks in, and you are holding a plain 3/3 with menace; above it the effect arrives stapled to an evasive body that keeps pressuring instead of trading. That gate is not one you trip on turn three by accident, so the swing is earned by grinding rather than gifted. The "up to one" wording is the smaller mercy, letting you decline when threshold is live but nothing on the board is worth touching. Menace does the closing work: a 3/3 a single blocker cannot stop finishes the games attrition sets up. The economy of the design is that the body pays for the card on its own, with the tempo swing layered on once the yard is deep enough to trigger it, so the creature is never a dead early draw and, late, a threat that reshapes the board as it lands.