Strategies:-
Shades are actually 'Beginner' units as their HP and Armor are very low and they can't fair well in battle although they are versatile. But since they are versatile, we can make some use of that special ability in which not many have.

Support:-
Shades, being 'Beginner' units have been assigned the eternal task of supporting. With the V ability, they can serve as GA when there is no AA or other GA around. This makes them quite useful when one side is lacking. Shades can't poc as they can get bashed up pretty badly by arbs. But cloaked shades can hurt arbs and balls alike pretty badly. With their low cooldown and fast movement, they rule over slow and weak units. But once anything that is stronger then a melee units comes into the picture, the Shade will most likely retreat first. With their cloak ability, they can support other units by wearing out the higher armored and HP units. Shades are also pretty useful in early stages to combat hit-and-run units as their range is pretty much the same as any other unit (other than Spirits). During the early stages, when there aren't much hit and run units, Shades can easily combat masses of imps and manticores. Imps, though having the ability to shoot bullets (hardly anyone uses it now) are still slower than a regular Shade. With a low cooldown and long range weapon, the Shade can easily pick off the Imps one by one.