You have at least ({E} magic symbol) ({E} magic symbol) .
You control at least six mana-producing lands, one of which can tap to produce at least ({B} magic symbol) and another of which can tap to produce at least ({G} magic symbol) .
Steps
Activate Squandered Resources by sacrificing a land, adding one mana of any color that land could produce.
Repeat step 1 until you have at least ({4} magic symbol) ({B} magic symbol) ({G} magic symbol) available and/or you control no other mana-producing lands.
Activate Aftermath Analyst by paying ({3} magic symbol) ({G} magic symbol) and sacrificing it, returning all land cards from your graveyard to the battlefield tapped.
When the lands enter the battlefield, Sporemound triggers that many times, creating that many creature tokens.
Activate Chthonian Nightmare by paying ({E} magic symbol) ({E} magic symbol) , sacrificing a creature and returning Chthonian Nightmare from the battlefield to your hand, returning Aftermath Analyst from your graveyard to the battlefield.
When Aftermath Analyst enters the battlefield, it triggers, causing you to mill three cards.