Storm Cloud gets launched into the air by casting after crouching off a zipline.

[dancedanceincineration]

By crouching off of a zipline or flying off the end of a zipline (jumping off the zipline doesn't work, haven't tested getting knocked off the zip) and then using storm cloud you get launched into the skybox.
Clips demonstrate this.

 

[d0ll10]

man is actually zeus lmao