On Hagara the Stormbinder, when the Iceshards starts rotating around the room, Ice Block works & as they are coming towards you, Blink will make you avoid being hit.
Invisibility did not work to dodge any mechanic on that encounter afaik.
I tend to keep Ice Block aswell, if an Ice Tomb is about to form on me, I just pop IB while it's still in the air, when it's falling down, it's too late & atleast this way you can tell your raid to focus the other crystal first or just stay alive longer as you won't take damage untill it runs out. Obvious but still worth mentioning I believe.

Just a warning to any mages that may go arcane on Zon'Ozz - it seems from our attempts last night that the debuff time reduction on mage armor is causing the Disrupting Shadows to detonate even if it is not dispelled.

I had no such problem in our attempts and eventual kill last night.

I think some folks were asking if Ice block worked on zon'ozz's void ball - it doesn't. When I tried last night, it went straight through me.

Im afraid it cant. The quoted post ment to say Cauterize, which you can use as a means to soak up HoT. This makes handling the HoT less stressfull, especially on 25man. It also actually gives you slightly increased DPS, seeing how you dont have to leave the twilight realm.

Combustion remains on its usual CD though.

I think that you confusing Cauterization and Combustion.

I think that Valarauca means that with 4T13 we can have a Combustion for each Hour of Twilight, meaning by this that we can use it to avoid the dps lost at this moment.

It might keep your dps higher for that particular moment but you aren't actually increasing your overall dps. You're just moving the point at which your Combustion increases your dps. If anything lining it up for HoT rather than when you grab a big Ignite is probably a dps loss overall.

Regarding Hagara, it was well known Pally/DK could Bubble or AMS and cross the Ice Bubble threshold and stay inside, among other ways. Mages too appear to have a way.

The trick appears to be needing to be mid-cast of something whilst you cross the threshold. This is easy for a Fire Mage to do with Firestarter and Scorch, half way through a Scorch cast pop inside. I confirmed this works reliably tonight not just for my Mage, but also for our Resto Shaman using their equivilant movement-while-casting ability too (Spiritwalker's Grace).

I tried Blinking in/out pass the barrier, but that didn't reliably work. Casting seemed to do the trick every time.

This is obviously much more useful on Heroic, whereby completing the Frost phase takes several laps. Furthermore, you will never have to move, even when targetted for Frostflake and even if a Frost Patch is directly under you, as standing in the patch itself does no damage.

Though not mage specific, I was also able to confirm this on Monday actually on my Hunter alt when I switched to Aspect of the Fox and Steady Shot cast into the bubble.

Pardon my ignorance, but I didn't quite understand. Does this mean you can remain inside the bubble and not take damage?

This has been fixed and casting scorch doesn't remove the debuff anymore aswell.