In the Decaying Winter: Last Strandeds mode, the Ulacylon Boss Wave is a 14.7% chance event occurring at Wave 20, featuring Zealot "Void" and elite soldiers. Survival requires using high-RPM firearms, utilizing crowd control to protect the VIP, and employing shoves to break Void's healing state. Learn more on the Decaying Winter Wiki . Ulacylon Boss Wave | Decaying Winter Wiki | Fandom