Planar Despair

On a board with a single basic land type, five mana buys a feeble -1/-1; the sweep only earns its cost as your manabase fans out, since domain prices the wrath in basic land types rather than land count. A deck assembling three, four, or five of them turns this into a scaling board wipe that erases an x/3-to-x/5-or-smaller field, and the structural idea (a sweeper whose magnitude is a function of how ambitious your mana is) is one of domain's cleaner expressions. The effect is symmetrical and total: it shrinks all creatures, yours included, with no exemption for fliers or anything else on the board. That makes it a poor fit for a creature-based deck, since reducing the field by -5/-5 also guts your own side. The asymmetry has to come from deckbuilding, around oversized bodies that survive the toughness hit, planeswalkers the sweep cannot reach, and game plans that win after the board is cleared, so a symmetrical line on paper becomes lopsided in play. It rewards a manabase doing double duty: the same dual lands and fetches that smooth a greedy four-color deck also scale the sweeper. That demand runs opposite to scaling effects that key off a single basic, like Mutilate counting Swamps and staying mono-black; this one wants land diversity as wide as you can stretch it. The ceiling is rarely reached, since most boards fold to -3/-3 long before a fifth basic type comes online, but tying spell power to the variety of lands you can assemble rather than their quantity is the whole bet of the domain cycle.