Also a little extra Info (which is also displayed ingame, but missed by alot of players)
You can have up to 3 Shadows at the same time by default.
Bladedancer Mastery gives you +1 max and the last node in the BD Passive Tree gives you +1, so 5 Shadows in total maximum, at the same time.
Also there are a handful more ways to spawn Shadows:
Lethal Mirage has two nodes to spawn Shadows, one leaves a Shadow behin 100% and the other has 5-10% chance, that Mirages stay as Shadows
Dancing Strikes has a node, where the 2nd Strike creates one Shadow
And the most niche one, in case you want to use Shadows for Marksman. Dark Quiver has a node, which spawns 1 Shadow per Black Arrow you pick up.