Lashknife

First strike is the upgrade that most reliably turns a one-for-one combat trade into a clean kill, the enchanted creature landing its damage before anything can swing back. What makes this Aura worth a second look is the payment scheme behind it: with a Plains in play, you can tap an untapped creature you control and skip the mana entirely. That "free" cast is never actually free, though. The creature you tap to pay for it is pulled out of the turn's combat math and can't use abilities that require tapping, so you are spending one permanent's usefulness for a turn to permanently sharpen another. The Plains clause keeps that discount tethered to a white deck rather than letting any color buy in on the creature-tap payment. This priced-in-tapped-creatures idea belonged to a short early-era experiment, part of a wave of designs that probed what a spell's cost could be made of beyond mana: life, discarded cards, exiled permanents, or here, the willingness to leave a body idle for a turn. The result is a small, telling artifact of a period when Wizards was still mapping the edges of what "cost" could mean on a card.