This is somehow related to 'DotA Technique"
You know how to use 'queue' in Warcraft III ?
Okay, it is simple
1. To 'queue', hold
Shift button, followed by your command. (example: hold Shift button and then order your unit to move (you will notice there is a flag on the ground, this indicates that you are using queue))
2. Next, try this: Queue your unit to move about 400 ~ 600 range from your original position.
3. Next queue, is to activate your spell via Hotkey
Remember, while queue, you don't let go of the
Shift button until you are satisfied
At step #3, First order your unit to move about 400 ~ 600 range from original position and then (still holding shift button, don't let it go!) activate your metamorphosis spell via Hotkey (if the spell's Hotkey is 'S', well, press S)
Remember, all those steps must be done while holding Shift button
Good luck