Activate Altar of Dementia by sacrificing another nontoken nonartifact creature.
When the creature dies, Missy's first ability and Skirk Alarmist trigger.
Resolve the Missy ability, returning the creature from your graveyard to the battlefield face down as a 2/2 Cyberman artifact creature.
Resolve the Skirk Alarmist trigger, untapping it.
Resolve the Altar of Dementia ability from step 1, causing target player to mill cards equal to the sacrificed creature's power.
Activate Skirk Alarmist by tapping it, turning the creature face up.
Repeat.
This crafty recursive loop turns Skirk Alarmist into a relentless engine by utilizing Thornbite Staff, which automatically untaps the Alarmist whenever a creature dies to keep the sequence going. You feed any ordinary creature to Altar of Dementia to mill your opponent, triggering Missy so she immediately resurrects the fallen creature as a face-down 2/2 Cyberman artifact creature. Skirk Alarmist then taps to flip that face-down Cyberman right back face up, readying it to be sacrificed to the Altar once more.