The oculus is an enemy that functions as the eyes for the Prowlers. They float across the map, and when they can see you, the prowlers won't be far behind.
A floating bloodstained eye with leathery wings that screeches loudly. Higher level ones have different color schemes like red or oily.
They will float around the map randomly until they find you. Once they do all the oculi AND all the Prowlers will aggressively close in on your location. When attacked they will fly up to try to dodge your attacks.
The basic oculus looks like a normal eyeball and shows up early. They don't have any kind of attacks and will simply follow you around.
They take the appearance of a black eye with a red iris and pupil. They can loudly scream at you to lower your movement, allowing the prowlers to find you faster and will sometimes shoot an eye laser at you when you are at low health.
The Ultimate oculus. Fast, aggresive and it's slowing scream can even stun you if you don't have the proper ear protection. Their massive speed and health, as well as their heavy use of eye lasers ,can make them as much of a threat as the prowlers.