This is mainly relating to fire/frost immunities as I am a mage, but what I'm wondering is basically is there anything significant taht is immune to either of these elements in raiding besides hydross (to frost) and a'lar (to fire)? I tried to find more, but was unable to see if any other boss mobs were immune. One question in particular I wasn't about to find the answer to is are the "water?" elementals (they might be poison, I'm not sure) that spawn during the vashj fight frost immune?

Since the 2.1 patch the mages in my guild (myself included) have been exerimenting a bit with different buiilds, including heavy frost and have found some pretty nice results that we didn't expect. We're just embarking into SSC and I'm curious if once we get hydross down to a ridiculously easy phase if we can specc out of fire or if there is a significant amount of frost immunity after that? I'm not sure if that's what we plan on doing, but I'm kind of curious if there is, to be prepared, and make an informed deicision, I can't find anything ot suggest any boss mods or adds in a boss encounter are immune, but I could be wrong.

Thanks in advance for any input.

Out of curiosity, Sapph wasn't frost immune?

Sapph in naxx was immune to frost, but I could care less about the old instances.

I thought that it was mainly those 2 bosses, but I wanted to double check before making any major gear/specc decisions.

Ultimately its going to possibly affect your choice wrt a tailoring specialization, but I dont think you can really consider the current boss encounters such that they make you pick a particular spec. The respec cost is so cheap now in terms of how fast it is possible to make money ingame, so I honestly wouldn't sweat your choice too much.

Since Hydross is immune to frost and Al'ar is immune to fire, it sort of "frees up" mages to spec either heavy frost, arcane/frost, arcane/fire or heavy fire since they're doomed to be inefficient, subbed out, or respeccing on one fight anyway. Heavy fire is ultimately highest dps, but heavy frost (don't forget imp blizzard!) has some control features which come in very handy, as add zergs are aplenty.

The solution for me was going full Arcane... CBA with being inferior or completely useless on some fights, much rather be 95% of 10/48/3 on most fights and much better on Al'ar. Also, Slow has turned out to work really well for us on some encounters.

This isn't a mage issue, but it fits into the thread nicely: What bosses in TBC raiding are poison immune and therefore a problem for Mutilate specced rogues? I know about Hydross and Void Reaver, so far.

I'm aware that at some point I'll just have to bite the bullet and spec Combat, but I'm a bit curious to see how long I can put that off.

and Frost for what its worth

It's only Karazhan, but Curator is immune to arcane. A bunch of the trash that looks like Curator was also immune last patch, but it may have been changed as I don't recall any immunities on my last run (Though I may have just been overjoyed by the changes to the mana fishes).

I am unsure why Blizzard thinks that these sorts of immunities are hilarious for mages to deal with. Basically it means you either don't do the fight or you pay to respec a number of times a week. Frankly I'm shocked they didn't make Nightbane immune to fire. I guess "We won't make immune bosses any more" was along the same lines as "Don't worry about Draenei getting fear ward -- we won't be using fear much."

Are there any shadow or nature immune bosses or trash in BC? I seem to recall the Green Dragons were nature immune.

I doubt they'll be making any such bosses with the current focus on making offspecs viable, unless they are heavy gimmick fights or have alternate dps outlets. As bad as fire/frost immune mobs are to mages, they aren't near as devastating as the above would be to shadow priests, elemental shaman and balance druids.

Could just be a fluke or other mitigating factors.