Complete all the Trinity challenges without wasting your time looking everywhere for these fellas
How to Find the Secret Bosses
By the end of the game you’ll activate the “Trinity Night” – a special game mode where you’ll be able to encounter 10 different bosses with familiar look, but a lot scarier than their basic counterparts.
Finding these bosses can take hours, since there’s no indication where to look.
You can follow the locations shown in the following video, divided by timestamps for each boss (best watched on YT for quick skips):