You control a face-down creature whose front face is a permanent card.
Steps
Activate
Bazaar Trader by tapping it, giving control of
Karlov Watchdog to an opponent.
During the opponent's turn, activate
Ashnod's Altar by sacrificing a face-down creature you control, adding ({C} magic symbol) ({C} magic symbol) .
When the creature dies,
Yarus's second ability triggers, returning it from your graveyard to the battlefield face-down as a 2/2 creature, and then not turning it face-up due to