You control up to five lands that can tap to produce at least ({4} magic symbol) .
Steps
Activate up to five lands by tapping them, adding at least ({4} magic symbol) .
Activate Altar of Dementia by sacrificing Peregrine Drake.
When Peregrine Drake dies, Nim Deathmantle triggers, returning Peregrine Drake from your graveyard to the battlefield, and attaching Nim Deathmantle to it.
When Peregrine Drake enters the battlefield, it triggers, untapping up to five lands.
Resolve the Altar of Dementia ability from step 2, causing target player to mill cards equal to Peregrine Drake's power.
Repeat.
If the lands can tap to produce at least ({5} magic symbol) , this combo nets infinite mana.