Zendikar's Roil

Landfall's clearest engine payoff: a standing permanent that turns each land you play into a body rather than a spent trigger, so the fetch that cracks for a second land, the extra land drop, the ramp spell that puts a land onto the battlefield all become Elementals instead of one-time value. The 2/2 green token is sized for the rate: big enough to attack and trade, small enough that a turn with two or three lands entering doesn't warp the board past what the mana can support. The cost is the tax. At five mana it lands after your early development is done, so you're buying an engine that only compounds if you keep hitting lands, and it wants a deck built to do exactly that: extra-land-drop effects, ramp that drops lands into play, fetches that snap for a second trigger. The standard line is to hold a land after resolving it so the first Elemental arrives the same turn, but the payoff is still back-loaded onto surviving turn cycles. Where Rampaging Baloths staples the same trigger to a body you can lose in combat and Avenger of Zendikar cashes it in as a one-shot swarm, this one is pure engine: no toughness to attack, no death trigger to punish, just a permanent that quietly converts land sequencing into a growing army every turn it stays on the table.