Rootwise Survivor

Survival keys off a condition most creatures spend the game trying to escape: sitting tapped when your second main phase rolls around. A hasty 3/4 that swings turns itself sideways automatically, so the reward folds into the aggressive line rather than bolting a separate activation cost onto it. The trigger drops three +1/+1 counters on a land you control, and because it resolves after combat, the newly animated 0/0 Elemental (a 3/3 once the counters land) cannot swing that turn; the haste it grants mostly frees it to tap for mana immediately, then it is ready to attack the following turn. Repeat the process and you keep manufacturing creature-lands, each a permanent body carved out of your mana base. The land-animation lineage runs deep, from Mishra's Factory forward, but most of that space asks you to spend mana every turn to turn a land sideways. This inverts the arrangement: an attacker you already committed hands the land its counters and its haste for free, and the counters stick, so the land stays a threat instead of reverting at end of turn. The real elegance is that the gate is self-referential. Being tapped is the requirement, attacking is how you get tapped, and attacking is what an aggressive green deck intended to do anyway, which quietly converts a row of lands into a slow but relentless second front.