Debatable. One could argue that having an integral part of your spec locked into a glyph is the worse situation.
Same flag as Ring's freeze, which is what interested me. If they've got the datamining right, which is a huuuuuge if, it could very well work like a very short duration RoF. I have to wonder how it'll DR if this is all correct.About Ice Nova, I checked it on wowhead, it says 1.5sec gcd, but as you say, the wowhead's spell details says "stun effect", but I guess (hope) it's a bug because the tooltip says "freezing".
The idea is that you don't even cast it until you're sitting on 2-3 FoF charges. It's not something that needs to be up 100% of the time, unlike the other two bombs. It has some pretty absurd potential given the right fight...
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Crystal has some potentially fun interactions, especially as Fire.