Alchemist's Vial

The cantrip is the whole point. Two mana for a card is the floor of acceptable rate, and this design accepts that floor in exchange for leaving a permanent in play you can cash in later. You replace the card immediately on entry, so the artifact costs nothing to hold, and the sacrifice clause rewards patience rather than reflex: keep it until you see a swing coming, then declaw one creature before combat resolves. The timing is where the card earns its keep, because it is not a Fog and it does not save you once you are already being hit. Used before attackers are declared, it strands a would-be attacker at home; held during your own turn, it keeps a chosen blocker out of the way of an alpha strike. Either way the window is preemptive, not reactive, which is a meaningfully different tool from instant-speed removal that answers a threat already on the stack or in the red zone. What it offers is a card now and a sliver of tempo insurance later, two resources that keep a slower deck from bleeding out without ever demanding a slot built around it. The structure is a common artifact-set staple, the kind of glue meant to smooth a curve and feed artifact-count synergies without being the reason anyone wins. It lives in the gap between pure card draw and pure interaction, committing fully to neither, which is precisely the role it was drawn up to fill.