Activate Commander's Sphere's first ability by tapping it, adding ({W} magic symbol) .
Activate Commander's Sphere's second ability by sacrificing it, causing you to draw a card.
Activate Ashnod's Altar by sacrificing Eternal Witness and Child of Alara, adding ({C} magic symbol) ({C} magic symbol) ({C} magic symbol) ({C} magic symbol) .
Child of Alara dies, destroying all nonland permanents.
Cast Faith's Reward by paying ({3} magic symbol) ({W} magic symbol) , returning all permanent cards put into your graveyard this turn to the battlefield under your control.
Eternal Witness enters the battlefield, returning Faith's Reward from your graveyard to your hand.