Ethereal Valkyrie

The foretell mechanic was built to smooth out mana across turns: pay a chunk of a spell's cost early, cast it later at a discount, and turn a dead draw step into a stored play. This card weaponizes that verb rather than just using it. Every enter-or-attack trigger loots one card deeper and then converts something in hand into a discounted, face-down time bomb waiting on the next turn's mana. The loop is what makes it more than a flying beater: draw fills the hand, foretell empties it at a two-mana rebate, and because the exiled card is castable even after the Valkyrie dies, the value survives removal. That last clause is the load-bearing one. Most repeatable card-advantage engines fold the moment the engine leaves the battlefield; here the exiled cards are already banked and payable regardless of what happens to the creature, so a chump-block or a kill spell only stops the next iteration, not the ones already stored. The tension it resolves is that raw looting (draw plus discard) is symmetric card neutrality; folding foretell into the discard half turns the "toss" into deferred casting, so the filtering costs you nothing in the long run. It is a design that took a set mechanic meant to help you sequence around a mana curve and rebuilt it into an attrition engine, one that rewards a hand full of expensive spells rather than punishing it.