Flowstone Armor

The mechanic worth studying is the lock between tapping and effect. The +1/-1 persists only while the artifact stays tapped, and the first line explicitly lets you decline to untap during your untap step. That converts a one-shot pump into a debuff you maintain by choice, which is the whole design. Point it at a creature with one toughness and it dies immediately: colorless, repeatable removal any deck can run. Point it at something larger and you hold the shrink open, keeping a blocker shaved down or a creature pinned a point nearer death so long as you commit the artifact to staying tapped. The constraint is that the suppression is both fixed and exclusive. The modifier is a flat +1/-1 that does not stack on itself, so it cannot grind a creature down over multiple turns, and because the activation includes the tap, only one creature can be held at a time. Redirecting onto a second target means untapping and reactivating, which ends the first effect the instant the artifact untaps. The decision each turn is binary: release this creature and seize another, or keep the same one held. Flowstone was the Rath-cycle keyword built around malleable stone reshaping itself, and the artifact honors that flavor by swapping a temporary buff structure for a maintained shrink. It is a control tool dressed as an artifact, rewarding the player willing to sit on a permanent and feed it mana rather than chase a single decisive swing.