Overgrown Battlement

The defender-matters mana engine in its purest mechanical form: a 0/4 wall that taps for green proportional to how many of your own creatures with defender share the board. The trick is that it counts itself, so the very first copy already produces a mana the turn it untaps, and each subsequent body that cannot attack becomes a green source that happens to block. That self-referential scaling is the whole reason the engine compounds the way it does: two of them on your side do not add, they multiply, because each is reading the same growing count of defenders you control. The body does the quiet work, big enough to wall off early aggression while it converts a stalled, defensive board into explosive acceleration. It anchors a deckbuilding shape that predates and outlives any one format: pack your side with defenders, generate mana far out of proportion to your land count, then dump it into a payoff that does not care about combat. Axebane Guardian later refined the same idea by fixing for any color rather than just green, but the Wall-tribal engine starts with this design: a creature whose worth is measured not in attacks but in how many of its kind sit beside it under your control.