Finding Delirium bosses

Twice now, while doing Delirium on random maps, a boss health bar has appeared, and I have been unable to find the boss. If Delirium wasn't a frantic mad dash to murder, maybe I could look around a bit, but unless the boss walks in front of me, I don't have time to find him. Maybe add a boss icon to the mini map?

Yeah, that's happened to me several times. I actually liked the delirium before they "fixed" it as you typically had enough time to clear all of the fog. Now you need a strong meta build to stay ahead of the fog speed. The mechanic is not fun and punishes slower clear builds. I wouldn't mind it so much if it wasn't prevalent on so many maps.