Banishing Knack

The trick here is that the spell grants an ability rather than performing one, which is what separates a combo enabler from an honest tempo play. The donated ability is a tap ability, so it inherits all the usual constraints: the creature has to have been under your control since your last turn (or have haste) before it can tap to bounce anything, and any flicker that re-enters the creature creates a fresh object that has never been granted the ability at all. The way to abuse it, then, is not flicker but untap: hand the ability to a creature you can untap repeatedly, and each untap buys another nonland permanent back to a hand. The most degenerate version turns the granted ability on a cheap creature alongside an artifact that costs little or refunds its own mana, so each bounce-and-recast loop builds a storm count or replays an enters-the-battlefield trigger. Left alone the spell measures out to nothing: one tap, one permanent returned, the ability gone at end of turn. That distance between its floor and its ceiling is the entire reason it exists, and it is why a "grant a repeatable ability" effect like this lives among combo pieces rather than fair midrange. What it grants is fully general, too: any nonland permanent, yours or an opponent's, at instant speed, for as long as the creature keeps untapping. The card asks one question, and it asks it of whatever shell picks it up. Is there an untap engine, and a payoff worth bouncing for?