Abaddon the Despoiler

Cascade has always been fixed: Bloodbraid Elf cascades when you cast it, once, at a value the card itself decides. This rewrites the keyword as a threshold you widen by playing the game correctly. The ability measures your opponents' losses this turn, not your own board development, so the payoff only opens once you have already begun the beatdown: chip in with a creature, land an early drain, and suddenly every spell cheap enough clears the bar and chains into free value on top of the damage that unlocked it. That circularity is the design point. The card wants you to attack, then rewards the attack with resources, then attack again. Grixis supplies both halves at once (burn and drain to raise the number, card advantage to refill), and the 5/5 trample body means it can be the one pushing the total higher without any help. It is a snowball engine wearing a beater's body, and the more life your opponents have already surrendered, the larger the mana-value window grows, so each subsequent cast fires off more for free. The build-around question it poses is unusually pure: how much damage can you guarantee before you commit your hand, because that number is the size of every free spell you get to chain afterward.