Activate Kiki-Jiki by tapping it, creating a token copy of Mardu Siegebreaker.
When the Mardu Siegebreaker token enters the battlefield, it triggers, exiling Kiki-Jiki until Mardu Siegebreaker leaves the battlefield.
Activate Umbral Collar Zealot by sacrificing the Mardu Siegebreaker token.
When the Mardu Siegebreaker token dies, Kiki-Jiki is returned from exile to the battlefield.
Resolve the Umbral Collar Zealot ability.
Repeat.
This clever loop turns Kiki-Jiki, Mirror Breaker and Mardu Siegebreaker into a self-sustaining engine by using the Siegebreaker's own entry trigger to tuck Kiki-Jiki safely away in exile. Because Umbral Collar Zealot is standing by to sacrifice the Mardu Siegebreaker token the moment it appears, it instantly breaks the exile bond and returns Kiki-Jiki to the battlefield ready to repeat the process. This endless cycle generates infinite enters-the-battlefield, leaves-the-battlefield, death, and sacrifice triggers, while the Zealot's surveil ability smoothly filters your library along the way.