Cavalier of Night | Mirror Image | Yahenni, Undying Partisan

Cards

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

Activate
Yahenni by sacrificing
Mirror Image.
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.
Resolve the
Yahenni ability from step 1.
Repeat.