Cavalier of Night | Mirror Image | Phyrexian Altar

Cards

All permanents on the battlefield (
Mirror Image as a copy of
Cavalier of Night).

Activate
Phyrexian Altar by sacrificing
Mirror Image, adding one mana of any color.
When
Mirror Image dies, its last ability from
Cavalier of Night triggers, returning itself from your graveyard to the battlefield as a copy of
Cavalier of Night.
When
Mirror Image enters the battlefield, its first triggered ability from
Cavalier of Night triggers; choose not to sacrifice a creature.
Repeat.