Cavalier of Night | Glasspool Mimic // Glasspool Shore | Altar of Dementia

Cards

All permanents on the battlefield (
Glasspool Mimic // Glasspool Shore as a copy of
Cavalier of Night).

Activate
Altar of Dementia by sacrificing
Glasspool Mimic.
When
Glasspool Mimic dies, its second ability triggers, returning itself to the battlefield as a copy of
Cavalier of Night.
When
Glasspool Mimic enters the battlefield, its first ability triggers, choose not to sacrifice a creature.
Resolve the
Altar of Dementia ability, causing target player to mill cards equal to
Glasspool Mimic's power.
Repeat.