Opponents control at least four aritfacts and/or enchantments.
({2} magic symbol) ({B} magic symbol) available.
Steps
Activate Altar of Dementia by sacrificing Dockside Extortionist, causing target player to mill cards equal to Dockside Extortionist's power.
Activate Dockside Extortionist's unearth ability by paying ({2} magic symbol) ({B} magic symbol) , returning it from your graveyard to the battlefield, giving it haste and exiling it at end of turn or when it leaves the battlefield.
Dockside Extortionist enters the battlefield, creating at least four Treasure tokens.
Activate three of the Treasure tokens by tapping and sacrificing them, adding ({2} magic symbol) ({B} magic symbol) .
Activate Altar of Dementia by sacrificing Dockside Extortionist.
Both Dockside Extortionist's undying ability and Void Maw attempt to exile Dockside Extortionist when it would be put into your graveyard.
Choose to apply the Void Maw replacement effect, exiling Dockside Extortionist.
Resolve the Altar of Dementia ability, causing target player to mill cards equal to Dockside Extortionist's power.
Activate Void Maw by putting Dockside Extortionist from exile into your graveyard, giving Void Maw +2/+2 until end of turn.