Hi, this is my first post trying to contribute to the forums, I know there is another frostwolf keep roof post but mine is easier to do (imo) I found this by exploring on my own.
1. First you have to go take the right at the chokepoint between FW GY and the horde bunkers. Then get to this location. Follow the arrows. (You can just walk through the arrow at the top)
2. Follow the arrows.
3. Follow this pathway.
4. Follow these arrows up. The dot is where you stand to start the part after that.
5. Mount up and jump forward, Tada! On top of FW keep.
Sorry if you're mad at me for posting my own version.
Have fun on top of FW Keep!