FOURTH COLOSSUS

It's a face off against another quadruped, this one with sharp feet and a tall giraffe-like neck. You will likely notice there is absolutely now way, no matter how hard to try, to climb up this thing. Since the sword identifies the weak points as being really high up and not visible you're going to have to find some other way to take on this beast.

The solution is as follows, it's now time to make use of all those entrance doors you passed just a little ways back. Ride the horse over there and wait as the Colossus follows you. The Colossus has a nasty attack where it stabs the ground with one of its front legs over and over again. Fortunately since they are so pointy, this attack is quite easy to dodge. Your goal now once you reach this point is to jump down and run through one of the doors. Descend down the stairs. The hallway here will lead you around in a square and back to where you came in. You can exit at any of the points. Pick one set of stairs and stand at the bottom.

Just wait here as everything shakes, and soon enough most shaking should stop entirely, when this happens what you need to do is stand at the bottom of each of the stairs and look up outside. At one of them you should see the Collossus' head, it is trying to peek inside to find out where you are. Let it peek. Run to the one on the opposite side and exit there. When you come out you will be behind the large beast and it won't notice you. If he starts moving at any point just stay hidden and soon enough he should duck down again, looking through the same door.

Run up to the Colossus from behind and note his tail, it has two ledges on it, bingo. It's a little bit high to run and jump, I find it easiest to just stand right beside it and jump vertically, holding R1 to grab on. I imagine you could also jump off your horse and grab it if you accuracy with the horse jump is good. The second you grab hold of the fur, the monster will know you are there and begin shaking its ass wildly. Hang on as best you can and climb onto the back, where you can just run without holding on too much. Keep running until you reach the neck.

There is a small weak point here like the first boss had, when you stab this with a weak stab twice, the boss will lower its head down. This is your chance to run along it, right to the top of the head above the face. You'll find the primary (and only) attacking weak point here. Grab hold of the fur and start using charged up stabs to defeat the monster. He likes to really shake his head around so it can be heard to hold on at times, but it's relatively safe to let go in between shakes here if you need a break. Since it's the only symbol, the boss dies when it's gone.