Sigil of the New Dawn's trigger, paying ({1} magic symbol) ({W} magic symbol) to return
Peregrine Drake from your graveyard to your hand.
Resolve
Deathrender's trigger, putting
Peregrine Drake from your hand onto the battlefield and attaching
Deathrender to it.
Peregrine Drake enters the battlefield, triggering itself, untapping up to five lands you control that can produce at least ({2} magic symbol) ({W} magic symbol) .
Resolve the
Altar of Dementia ability from step 1, causing target player to mill four cards.