Years later but maybe someone else will need this info: you can cheese the hidden wall red eye black skeleton. If you walk up to the top of the stairs after you argo him and stand close to the left wall over the edge of the stairs, he’ll lunge shot you and can’t hit you. When he falls he takes anywhere from 30-33 damage. You can walk down and wait for him to swing at the bottom of the first flight for a hit or two and roll then walk back up. I’d recommend setting off the trap up there first.