Lich's Mirror

The most fundamental loss-replacement effect ever printed: not "you don't lose," but "you reset to the opening state." Most last-stand effects buy a turn (Angel's Grace) or staunch the bleeding (Platinum Angel keeps you alive only as long as it survives); this one rewinds everything to a fresh hand, twenty life, and only your opponents' permanents left standing. The catch lives in the verb "shuffle into your library": every permanent you own goes back, so the reset costs you whatever position you had built. You survive lethal at the price of starting over, which makes it a worse deal the more invested you are and a better one the more desperate. Because the replacement effect sweeps this very artifact into the library along with everything else, a single Lich's Mirror saves you exactly once: to refuse death a second time you have to find and resolve another copy, or recast this one. That self-consumption is the structural cost the rate hides; it is a one-shot reprieve, not a standing wall. Functionally it asks a strange question for an artifact at this mana value: not "what does this do for me now" but "how much of my built position am I willing to feed back into my own deck to push a single loss into the future." A loop piece, a combo enabler, a Johnny's safety net, and almost never a fair one.