This is my interpretation of the jutsu, and I am gonna leave it at that.
At first the jutsu looks like some acute form of a crow summoning.
But I believe he does actually more or less, put the crows under a genjutsu using his sharingan. And if you notice the crow clone has only be used while heavy genjutsu was applied.
So in order to use the crow clone, you must first put the users under a sharingan genjutsu.
However, I am not gonna void the post because it is a PF. SO learn your lesson now and carry on.