here's just some things i think could be changed: make it stun instead of giving smoke screen, and the smokescreen is bugged now and then. it says "1%" and have a fist symbol... but what i really think should be changed, is their singing. instead of making it sound like they sing underwater, it would be more amazing if they had an Angel-like voice. you changed the sound of Seraph, and i think, since sirens use their song to trick sailors, it should me more soothing, and clean. kind of like the voice "The little mermaid" had when Ursula steals her voice, thats more enchanting :)
so yea, would be nice with a beautiful voice and a stun... more useful because of storms low health :) Thanks, nice job on Zafaria and the other spells :D