Collective Restraint
Propaganda taxed every attacker the same: two mana a head, no matter what your manabase looked like. This rewrites that toll to scale with land diversity, and the scaling carries the whole design. Stretch your lands across all five colors and each attacker owes before they can swing your way, a wall steep enough to halt an aggressive board outright rather than merely slow it. The strength here is not printed on the card; it is printed in your land base. A mono-blue control shell collects a feeble single-mana toll, barely a speed bump. A sprawling five-color brew turns the same enchantment into a near-impassable fog that recurs every combat. That conditional ceiling is the tension domain always carried: the effect is only as powerful as the manabase you were already incentivized to build, so the decks that wanted this protection most (greedy, color-hungry midrange and control) were exactly the ones positioned to extract the full toll from it. It rewards committing to fragile, multicolor manabases as a defensive virtue, the precise deckbuilding the domain mechanic was meant to encourage. The result is a deterrent that pays out in proportion to ambition: the more colors you reach toward, the higher the price every attacker pays to get past it.

