Flowstone Wall

The Flowstone mechanic from the Rath cycle treated the lithified land itself as a combat variable, and this is its defensive face: a wall whose statline is a mana-gated dial rather than a fixed value. The 0/6 body is already a hard blocker, but the repeatable : +1/-1 is the wrinkle. Each red mana shifts the line toward offense, swapping toughness for power, and that conversion is sharply self-limiting. Pump it to 6/0 and it falls over on the spot; every activation narrows the margin it has to survive the block. The discipline lives in the cost itself: you pay to make the blocker bigger, but each payment walks it closer to its own grave, so spending exactly enough to trade with an attacker (and not a point more) is the entire skill of piloting it. Because it cannot attack, the offense the pumps imply is purely a blocking-step calculation. The math has to be settled after blockers are declared and before combat damage resolves: activate too late and the toughness loss is wasted, activate too eagerly and you have killed your own wall for nothing. The whole conceit of Flowstone was that defense and offense are the same malleable resource measured from opposite ends, and this is the clearest statement of that idea on the defensive side: a static-looking creature that is really a stack of small, irreversible decisions.