In Chapter 2 of Leon's campaign, after entering the cathedral, you must solve some puzzles to open the main chamber door in the center of the altar. Afterwards, you will encounter the Lepotitsa. It infects many humans in a short time by releasing C-Virus gas. You must save at least two females in the cathedral. To do this, shoot it as quickly as possible while remaining at a safe distance. However, do not position yourself too far away or you will lose sight of it and it will infect too many people. If you do enough damage, it will expose its weak areas and get on its knees. Once this happens, get close and perform a melee attack for increased damage. Note: This will require a large amount of ammunition on the higher difficulties. Consider doing this after completing the campaign, in order to have better weapons and perhaps infinite ammunition.