Cast Illicit Masquerade by paying 3. When it enters, its first ability triggers, putting an impostor counter on Skullbriar.
Cast Perigee Beckoner for its warp cost by paying 1.
When Perigee Beckoner enters, it triggers, targeting Skullbriar.
Activate Umbral Collar Zealot by sacrificing Perigee Beckoner.
Activate Umbral Collar Zealot by sacrificing Skullbriar.
When Skullbriar dies, Illicit Masquerade's second ability and Skullbriar's ability granted to it by Perigee Beckoner trigger.
Resolve the Skullbriar trigger, returning it from your graveyard to the battlefield.
Resolve the Illicit Masquerade trigger, failing to exile Skullbriar as it has left your graveyard and returning Perigee Beckoner from your graveyard to the battlefield.
Resolve the Umbral Collar Zealot ability from step 5.
Repeat from step 3.
This clever loop relies on Skullbriar, the Walking Grave's unique ability to retain its counters and memory across zone changes, allowing it to act as an infinite sacrifice engine with Umbral Collar Zealot. When you sacrifice Skullbriar, both Illicit Masquerade and the temporary death-trigger granted by Perigee Beckoner trigger simultaneously, letting you loop Perigee Beckoner back and forth from the graveyard. Meanwhile, Illicit Masquerade's exile clause fizzles because Skullbriar has already moved zones, ensuring the pieces can reset endlessly while Umbral Collar Zealot smooths your draws with infinite surveil triggers.