Earth Tremor

Damage that scales off land count is an old red idea, usually welded to a fixed-cost sorcery that rewards reaching the late game with a full manabase: Seismic Strike runs the same math one turn slower. Moving that scaling onto a fixed-cost instant is what this design is really about. Four mana buys a damage figure that grows with your board, so early on it is a below-rate answer that still reliably clears four or five toughness worth of threats, and its reach keeps pace as the game goes long, eventually large enough to bury the biggest creature or planeswalker an opponent can present. The instant speed does the heavy lifting. A sorcery version forces you to spend it on your own main phase; holding this up lets you ambush an attacker mid-combat or drop a planeswalker on the opponent's turn without tapping out and exposing yourself. The count is read on resolution, which mostly matters for staying flexible about when you commit the effect rather than for squeezing extra lands into the total. What the card asks in return is patience: the turn it lands, it is doing a job cheaper burn handled several turns earlier, and its scaling only pays in slow, land-heavy games. That confines it to grindy decks that want removal to keep growing with the board instead of capping at a fixed three or four, and that never point it at a face, because the printed target line does not allow it.