Activate Ashnod's Altar by sacrificing Avenger of Zendikar adding ({C} magic symbol) ({C} magic symbol) .
Avenger of Zendikar dies, triggering Nim Deathmantle, causing you to pay ({4} magic symbol) to return Avenger of Zendikar from your graveyard to the battlefield, and attach Nim Deathmantle to it.
Avenger of Zendikar enters the battlefield, creating at least two 0/1 Plant tokens.
Activate Ashnod's Altar by sacrificing a Plant token, adding ({C} magic symbol) ({C} magic symbol) .