Cast Chronozoa by paying 3. It will enter without a time counter on it due to Solemnity.
Activate Umbral Collar Zealot by sacrificing Chronozoa.
When Chronozoa dies, it triggers, creating two token copies of itself that also enter with no time counters on them due to Solemnity.
Resolve the Umbral Collar Zealot ability.
Repeat from step 2 using a token copy of Chronozoa instead.
This clever loop relies on Solemnity to completely neutralize Chronozoa's vanishing mechanic, ensuring it enters the battlefield with zero time counters instead of three. Because of this, whenever you sacrifice that Chronozoa to fuel Umbral Collar Zealot's ability, its death trigger immediately sees an empty counter tally and replaces it with two brand-new token copies. Those tokens also slip past Solemnity's restriction to enter without time counters, giving you a fresh supply of sacrifices to repeat the cycle indefinitely for infinite death triggers and surveil.