Mordekaiser W Suggestion
Make it castable on location OR friendly target, with the damage scaling relative to the target's HP. That way it can still be the most effective when used on a teammate, it can be used on creeps in lane to help push waves, or it can be an escape tool to give him a speed boost. If you want to run from him, just don't run towards the cloud. You could balance it to not be an overpowered dueling tool by altering the damage so that it's not too bad in the base form and needs a friendly target to scale into decent damage.