Thieves' Fortune

Card selection priced around the one thing a Rogue deck has to do anyway: land a hit. Paid in full, looking at four and taking one is a fair Impulse-style dig, the kind of effect no deck builds toward. The prowl clause is where it earns its slot, dropping the cost to a single blue once a Rogue has connected for combat damage that turn. That gating matters because the discount only ever arrives on a turn you have already swung successfully, which makes the spell a second-main-phase refuel rather than an end-step trick on the opponent's turn: prowl reads "this turn," and you attack on your own. The instant typing still buys you a window, letting you hold up the dig and decide between casting it post-combat or sitting on the mana for a counterspell or another instant. Prowl as a mechanic was always about welding a deck's spell half to its creature half, asking you to commit to the beatdown before the reward comes due, and this spell makes that contract unusually legible: a deep, cheap look, but only after the board work is done. The Rogue type line ties it to a kindred shell thematically and lets future Rogue-matters cards count it, though as an instant it can never feed prowl itself; the connecting is always the creatures' job.