Corpius is the first boss you’ll encounter in Metroid Dread. You’ll find him in Artaria soon after defeating your first E.M.M.I. drone. Corpius is functionally a tutorial boss, so he shouldn’t provide too much trouble, but make sure you’re fully stocked on health and ammo before challenging him.
In Corpius’ first phase you’ll have to engage him at a range. As you might have seen in the intro cutscene, Corpius has a long, whip-like tail that can be used to attack Samus from afar. Keep your distance from him and prepare to jump whenever you see his body begin to shiver. Corpius’ only weak point is his face, so concentrate all your missile fire on that spot. Your shots will bounce off his tail without causing any damage, so don’t waste your ammo.
After a brief cutscene plays, Corpius will become invisible and transition into phase two of the fight. While invisible, Corpius’ only weak point is the glowing core held near the tip of his tail. This core is vulnerable to your basic arm cannon in addition to your missiles. If you want to conserve your missiles, try hitting the core with your charged shots, but bear in mind that your missiles will do more damage.
Soon, Corpius’ invisibility cloak should drop, revealing that Corpius is now facing away from you. Quickly run towards him and slide underneath with the ZL trigger, but be on your guard. As soon as Samus slides out to Corpius’ other side, a melee counter trigger will appear. Corpius will attempt to jab you with his tail once you slip past his face. Press X to counter the jab and then hold the right trigger. A combat takedown animation will play that allows you to pump Corpius with nearly 15 missiles while keeping yourself free from damage.
Once you’re on Corpius’ other side he’ll begin to use two new attacks, both telegraphed by his throat beginning to fill with bile. In his first attack, Corpius will cover the floor in a poisonous gas that will slowly damage you as you stay in contact with it. You can avoid this by jumping into the walls of the arena and latching on to the blue, magnetic surfaces. In the second attack, Corpius will launch an arcing projectile through the air towards Samus. You can shoot this projectile out of the sky, and if you succeed you’ll be rewarded with a small refill on health and ammo.
You have to beat Corpius here or his pattern will cycle again
If you fail to defeat Corpius during this stage, his attack pattern will cycle through once more. This will require you to once again destroy the core in his tail whilst he’s invisible before sliding under his body and countering his jab. While this may sound punishing, this does not reset his health. If you are can consistently counter his jab, it may even be worth it to wait out the timer on purpose, so as to trigger the free damage cutscene a second time.
After a few minutes, Corpius should shake his head and begin to charge at Samus. This cutscene indicates that the boss fight is now complete. As soon as the scene ends you will be able to collect the Phantom Cloak from Corpius’ body.