Unleash the Inferno

Seven damage at instant speed is comically more than any creature or planeswalker needs to die, and the overkill is precisely the point: it is a resource to be spent. The excess damage clause converts a wildly oversized removal spell into a second effect, cashing the surplus into destruction of an artifact or enchantment whose mana value fits inside the leftover points. Kill a 3/3 and you have four damage to spend against a signet or an aura; blank a fresh planeswalker and there is barely anything left over, so the shape of the second mode nudges you away from the biggest thing on the board, since the more the first target absorbs, the less you can spend on the second. That coupling is what justifies four mana across three colors: Jund gets a removal spell that answers threats no fair deck should have trouble with, then folds in a slice of the noncreature disruption those colors normally pay for with a separate card. The tension is that both halves want different targets. Overkill exists to generate excess, but the meaty threats that most justify seven damage eat most of it and leave little behind, while the small bodies that leave the most excess are rarely worth an instant this expensive. Reading the board for where the two effects line up (a mid-sized threat plus a cheap permanent you also want gone) is the entire skill of the card, and the reason it plays more like a tempo-and-value swing than a clean point of removal.