Pure // Simple
The unifying idea is dependence, but the two halves attack different kinds of it. Pure answers the multicolored permanent: the gold creature or gold enchantment whose very existence leans on a manabase stretched across two or three colors, destroyed cleanly with no clause about counters or regeneration. Simple sweeps every Aura and Equipment at once, the cards that do nothing on their own and exist only to make a creature better. One half punishes a threat that needs a wide manabase to cast; the other punishes a threat propped up by attachments. What ties them together is that neither half touches a mono-colored creature standing unadorned: each is an answer to a permanent that relied on extra structure to get where it is. The cost split tracks the theme. Pure asks for red and green, the colors most likely to be staring down a gold bomb and wanting it gone before it takes over. Simple asks for green and white, the colors most invested in building creatures that Auras and Equipment would otherwise be dressing up, and so the ones best positioned to clear that clutter on their own terms. As split-card design, it is a small thesis on what removal can target once it stops asking "is this a creature?" and starts asking "what is this permanent leaning on?"
