After you’ve completed the puzzles in the Umbrella laboratory you’ll be tasked with another big boss fight against Birkin again. This time, the g-virus has completely taken hold of him and he’s the most powerful that he’s been of the three encounters you have with him.
While he is more powerful, his weak spots are still the same. You are going to want to shoot for the eyes to weaken him and then when he gets to his weakest state a group of eyes will come out of his abdomen and you must shoot that as much as you can.
The trick to beating Birkin in this final encounter is to tack accurate shots because there is usually only one eyeball to hit until the big mass of eyeballs comes to the surface of his skin. Birkin can be beat pretty quickly if you take accurate shots. If not, and you miss too often, it’s likely that he’ll close the distance gap and use his powerful melee attacks.
He also has a powerful throw attack as well in this encounter where he can rip things off the environment and throw them at you. If you need a quick look at what the fight plays like you can watch the video below to see how the fight plays out.