Fertilid + Crystalline Crawler + Avenger of Zendikar + Ancient Greenwarden + Conspiracy

Fertilid

Crystalline Crawler

Avenger of Zendikar

Ancient Greenwarden

Conspiracy

How it works

1. Activate Fertilid by paying 1 and removing a +1/+1 counter from it, causing you to search your library for a basic land card and put it onto the battlefield tapped.
2. When the land enters the battlefield, Avenger of Zendikar's second ability triggers twice, putting two +1/+1 counters on each creature you control.
3. Activate Crystalline Crawler's first ability twice by removing two +1/+1 counters from it, adding 1.
4. Repeat.