Ok so when the round starts if your CT go up the underground passage way then go up the stairs now the wall is misformed shoot it until it breaks go thru the opening until u get to the end then go down to the last 2 or 3 stair crouch and tap e and move around remember to check if the door is open once ur inside zombies can only get you one way they have to back break the blood and guts room if they do that reatreat downstairs for the final battle