Conflagrate

Two payment systems for the same effect, and the gap between them is the whole design. Cast from hand, the front side is a fair, expensive divided-burn spell: the cost means you pay twice X in generic mana, so each point of damage runs you two mana, a deliberately stiff rate for the freedom to split it among any number of targets. The flashback rewrites that economy completely. From the graveyard, X damage costs plus discarding X cards, converting your hand directly into burn at one card per point. That discard reads as a tax until you notice what fills a graveyard-centric deck's hand: reanimation targets, threshold fuel, madness payoffs, anything already bound for the bin. In a shell like that, the discard stops being a cost and starts being the throughput. The split-damage clause carries the other half of the card's identity, letting it function as a one-card answer to a board of small creatures or a precise reach spell hitting a planeswalker and a player at once. The two modes rarely fire in the same game, and that separation is the point: you choose measured removal now or a hand-emptying finisher later, and either way the discard pushes the deck toward treating the graveyard as fuel rather than a loss column. That requirement is what keeps it out of generic burn shells and pins it to strategies built to feed the yard, a narrower and stranger home than most X-spells claim.