Cast Living Death by paying ({3} magic symbol) ({B} magic symbol) ({B} magic symbol) .
Holding priority, cast Naru Meha by paying ({2} magic symbol) ({U} magic symbol) ({U} magic symbol) .
Naru Meha enters the battlefield, copying Living Death.
Holding priority, Activate Altar of Dementia by sacrificing Naru Meha, causing target player to mill two cards.
Resolve the Living Death copy, exiling all creatures from graveyard, then sacrifices all creatures, then putting all cards exiled this way onto the battlefield.