Annihilating Fire

The double-red pip and the extra mana sit above the cleanest burn, so the exile rider has to justify the difference, and it does, by slamming the graveyard door on whatever it kills. Against a persist creature like Kitchen Finks, a creature holding an undying counter, or anything earmarked for reanimation, the dead body never reaches the yard: it goes straight to exile, denying the second life a returning counter or a graveyard recursion shell would otherwise grant. The clause is conditional on the damaged creature actually dying this turn, whether from the burn itself or from anything else that finishes it. Any creature that took the three and then dies this turn is caught by the rider; but one that replaces its death with regeneration is untouched, because a regenerated creature is never destroyed and never dies, and the exile replacement has nothing to grab. That trade (steeper cost and tighter color requirement for a kill that stays dead) is the entire design. It is removal built for a world where death is a launching point rather than an ending, where the question is not whether you can deal three but whether three will hold. Plenty of red answers what is on the battlefield now; far less of it answers what the battlefield will try to rebuild from the yard, and that is the narrow but durable job this fills.