Colossus 12 is not obvious, nor is it really very fun. I'd have cut this one. I used the back of the colossus to climb up, but he's a rather swift joker at times, so it took a while to actually snag his back this way. Any other ways?
Colossus 13, on the other hand, was totally obvious and extremely fun.
Let me put it this way: if you've read Dune by Frank Herbert and, like me, dreamed of what it must be like to ride a sandworm, then this is better. It's like catching and riding a flying sandworm. It's just that cool.
After Colossus 12 there is a short cut scene. Six riders on horses appear to be coming toward the shrine, but are still a little bit away. Five horses are black and one is white. A close-up of the guy on the white horse shows he's wearing a mask (reminds me of the masks on the little guys in Princess Mononoke) and says that it isn't far to go.