User blog comment:Miskos3/Fairy Tail Chapter 391: Gray vs. Silver, Review/@comment-4449950-20140704071540/@comment-7418318-20140704084249

Apart from negating his character development in the Galuna Island Arc, it would be foolish to use Iced Shell now. Deliora can eat Ice Magic and Iced Shell is Ice Magic. Sure there is a chance that the special properties prevent it from being eaten, but can you really take that risk with a spell that effectively kills you?

You only use such a last resort suicide technique if you are reasonably sure it'll work (unless you want to kill yourself, which Gray doesn't).

But IF Gray ends up casting it, maybe he'll get fully absorbed by Deliora and then his and his father's disembodied souls can battle against Deliora from within the body.

Would be interesting if afterwards Gray forms a kind of ice golem as his new body, since his old one was destroyed.