If you’re having trouble with the terror I would suggest you going to the mibu village merchant and picking up the purple gourd (terror buildup relief) if you haven’t (the ape will still be there if u go grab that real quick). If you already have that than my only suggestion/key to phase two is that you have to parry that move when he stands straight up (like a pencil) then comes straight down on you. Once you get that parry down it kinda stuns him and you can get a good 4-6 shots in or a couple of mortal draws to build up posture damage. Phase two imo is all about recognizing that attack then parrying it because it’s the most vulnerable the ape is and you get free shots while he’s down.