User blog comment:JmLyan/CB1 Sorcia, the Spellbound/@comment-24403085-20150318164054/@comment-7481207-20150318164723

The E has tactical uses. While you can just use it for the damage, you can potentially make enemies waste spells or be silenced by it. Also, the rest of the kit is designed around enemies casting spells, so forcing an enemy to cast a spell has additional benefits.

The Q is there because the kit needed a low cooldown spell to spam. Many champions in LoL have simple abilities like this that are boring on their own, like is just a targeted nuke with a refund function.