Avenger of Zendikar gives green decks an immediate board and a way to keep growing it. When it enters, it creates a 0/1 Plant token for each land you control. Each land that enters afterward can put a +1/+1 counter on every Plant you control, turning that initial group of small tokens into a serious combat force.
Fetch lands such as Misty Rainforest provide two landfall triggers: one when the fetch land enters and another when the land it finds enters. If you can wait until Avenger and its token-making trigger have resolved, those triggers can grow the full Plant army. Exploration helps by allowing another land play, while land-ramp spells develop your mana and improve the creatures already on the battlefield.
Token doublers such as Parallel Lives increase the number of Plants, and Doubling Season can improve both the token count and the counters added afterward. Craterhoof Behemoth offers a separate finishing route by giving the team a large boost and trample. Finale of Devastation with X at least ten can grant haste as well, allowing newly made tokens to attack during the same turn.
Without haste or another immediate payoff, the Plants need time before they can attack. Keep protection available when possible, and consider holding a land play until after Avenger enters so you can begin growing them immediately. The card fits ramp, lands, and token strategies that naturally reach seven mana and want one creature spell to establish a threatening board without needing an existing army.
