What event decided the battle of Krina in Sundiata's favor?

Sundiata shoots his magic arrow and nicks the sorcerer king, at which point the sorcerer king feels his powers leave him. He looks to the sky and sees a black bird, an omen of misfortune.

Soumaoro retreats in fear, which disheartens the Sossos and causes them to flee. "Who can tell how many Sossos perished at Krina?" the griot asks.

hahahaha I wish there was magic during fight><3