Volcanic Torrent

The clever bit is the loop between the two abilities. The damage scales off spells cast this turn, and cascade is itself a spell-casting engine bolted onto the front of the card: casting this triggers a cascade hit, and if that free spell in turn casts another (or you chain your own castings around it), the counter climbs before the sweep resolves. So the card is deliberately built to undercount when played alone and reward a turn full of casts. Play it cold off an empty turn and it usually deals two: one for itself, one for whatever cascade turned up (assuming you choose to cast it). Deploy it as the capstone of a spellslinger turn and the same words wipe an entire board of creatures and planeswalkers, one-sided against your opponents. The asymmetry is doing as much work as the scaling; this is a sweeper that never touches your own side, which lets a go-wide or storm-adjacent deck fire it into a full table without collateral. The five-mana cost buys the cascade trigger, but the real price is the deckbuilding one: a card whose ceiling only exists if the rest of your turn feeds it, and whose floor is honest about it. It belongs to the family of red mass-damage effects that punish creature-heavy boards, but where most of those name a fixed number, this one hands the dial to the pilot and asks how much work they did before casting it.