Mission 3 on the third floor? Where the guy is waiting for you when you when you first enter the floor?
mostly hes just right there when i enter the floor, i get killed instantly since my health is low, just a skill issue tho, i did manage to beat it :
Thanks for the extra detail! Yeah, the game can be challenging when entering a doorway you always have to be ready to shoot. The next update will include a bullet-time ability, which should help in situations like this.