Karn's Sylex

Named for the device that sundered Argoth in the game's oldest lore, and the design honors that history by making planar-scale destruction its terminal, self-consuming function: an act the card performs exactly once. The activated ability is a scaling one-shot wrath, letting you set the mana value ceiling precisely where the board demands, from clearing only two-drop clutter up to scouring everything at that value or below. The "or less" clause is symmetric, so a larger X drags your own cheap mana rocks down alongside the enemy field; the sweep discriminates neither by owner nor usefulness. Because it destroys rather than exiles, everything it kills feeds death triggers and lands in the graveyard for recursion; only the Sylex itself is exiled, as part of the cost. Entering tapped and firing only at sorcery speed hands the table a full turn cycle to react before it goes off. The static line does very different work, and it functions as a hard lock rather than a payment: shutting off life as a casting or activation resource answers a specific school of play, the fetch-cracking, Phyrexian-mana, "life is just another fuel tank" approach. Those engines simply stop, and the artifact stops them without touching a single permanent. It is a rare piece that pairs a scalable board reset with a targeted tax against life-as-resource strategies, two roles that almost never share a card.