Activate Altar of Dementia by sacrificing Sister Hospitaller, causing target player to mill cards equal to Sister Hospitaller's power.
Activate Altar of Dementia by sacrificing Junji.
When Junji dies, it triggers, returning Sister Hospitaller from your graveyard to the battlefield.
When Sister Hospitaller enters the battlefield, it triggers, returning Junji from your graveyard to the battlefield, and causing you to gain five life.
Resolve the Altar of Dementia ability from step 2, causing target player to mill cards equal to Sister Hospitaller's power.