Mimic

Two mutually exclusive futures live on the same object, and the design forces you to pick between them. The first is the standard Treasure line: tap, sacrifice, any color of mana appears. The second animates the artifact into a 3/3 Shapeshifter for two mana. What makes the choice bite is that the paths cancel each other, because the mana ability consumes the artifact as a cost. Spend it for fixing and it heads to the graveyard, with no body left to animate; hold it as a threat and you never bank the color. That trade-off is the real decision the card asks for, and it lifts the animation clause above filler stapled onto a piece of ramp. Where most mana rocks settle into inertia once the manabase is built, this one carries a latent 3/3 that switches on for only idle mana, useful across a stalled board or as an ambush blocker. Note what the animation does and does not grant. It becomes a Shapeshifter, the tribe, but without changeling it reads only as Shapeshifter, not as every creature type at once; the animated rock answers to Shapeshifter-matters effects and copy effects, not to a broad tribal roll call. The choice is never abstract. Early, it is fixing you eventually cash in. Late, it is a threat you commit to keeping. What it cannot be is both, and reading which one the board wants is the whole play pattern.