User blog comment:FairyRaven/Fairy Tail Chapter 391: Gray vs. Silver, Review and Commentary/@comment-5303512-20140704145014/@comment-7418318-20140704160612

I would hate that to happen. The very reason why Iced Shell can make eternal ice, rather than just long-lasting ice is because it uses the very life of the caster. It shows that a life is more important and in a way more powerful than magic.

If Iced Shell could be cast with only magic, without sacrificing the body, it'd be like saying life and magic are equal.