A crow storm was the name given to the move that Lucius used and considered the most devastating move a Bloodcrow Knight was capable of unleashing.
A move that Amir had learned about a lot, and he had even considered learning it when he reached the rank of Master, all in hopes of dealing with his enemies.
Of course, by the time he entered the ranks of Master, he started to notice how lacking it was in comparison to the things he created on his own.
His main issue was the resources this move required. Although you can control a powerful army of beasts, it still makes you weaker in the end. And if not for support for expensive potions, this move can be considered suicidal as well.
Amir was not the kind to leave his life to chance, nor did he believe the crows he summoned would ever be able to secure him completely.