Um, what kind of fog are you wanting? Attack's missing % of the time, silencer/disable, or tower disabler? You want the Mirror Image as in.. divide into how many?
If you have any knowledge of the Trigger Editor, add the ability of Mirror Image (you make that ability in the Object Editor) on your casting unit with the Trigger Action(Set the level of that ability with the level of your "fog" ability using "Arithmetic"), use the Order Trigger to order your casting unit to "Orc Blademaster : Mirror Image" to get the secondary effect. As for the Fog....
Copy it off a standard Fog ability like the Human Cloud ability the Bloodhawk Rider has, convert it into a hero ability, give it multiple levels (If required), and set the Data part the way you want it. After that, add that ability to your Hero.