Brain Suckler

This is a flying enemy spawned by the Nebula Pillar during the Lunar Events. It can latch onto the player's head, greatly reducing vision and dealing large amounts of damage. It appears to be a reference to the 'Headcrab' enemy from the Half Life games as it drops the Nebula Headcrab banner and has a similar attack (headcrabs jump to a persons head and take over the nervous system while this jumps on top of someones head and inflicts you with a debuff). It also looks similar to the Headcrab, with a bit of Metroid thrown in.

History
Suceur de Cerveau