Brightflame

You point the spell at one creature, but the burn fans out to everything sharing any of that target's colors, so a gold creature pulls two whole color buckets of the board down with it while off-color creatures walk away clean. That conditional footprint is the whole proposition. Against a mono-colored board it functions as a sweeper for that color regardless of who controls the creatures; against a five-color table it becomes closer to a board reset that takes your own creatures along with it. The lifegain rider scales with the carnage, quietly turning a clearing into a life-total swing, though it never gives you any handle on the spread. Every cast poses the same evaluation: which color is the opponent overexposed in, and what of yours dies in the blast radius. Radiance, the mechanic that hangs a spell's reach on the colors already in play rather than on the caster's choice, never returned as a recurring keyword, which leaves this as one of the cleaner surviving artifacts of an experiment in making removal's footprint a property of the board state instead of the controller's discretion. Where a conventional sweeper rewards counting toughness, this one rewards reading the colors in play.