A month ago my guild managed to put down Gruul for the first time and enter Serpentshrine. We've been slow to make progress on him due to lack of Nature/Frost resist gear but for the past week we have been beating our heads against him. One of the things we noticed was the huge burst damage due to crushing blows on the tank. Every single other elemental mob's damage in the game can be mitigated through the use of shield block. Hydross seems to defy this mechanic as shield block fades each and every time we use it on him. We decided that shield block was useless to cast as it didn't seem to work.

I was curious to hear how other guilds have faired with the huge crushings without the use of shield block.

Elemental damage ignores shield block. Your tank might as well use a 2h =)

This is not true. Some elemental damage mobs you can block and some you can't, and there is no clear rule governing it that I can tell. The only theory I have is the ones you can block may have a partial physical component to their damage, like core hounds

It's Serpentshrine, FYI.

Use flasks, and hope for some good luck. Frankly we tank him sometimes at 250% in the NR phase just fine. I run 295 unbuffed NR, and 490 defense with the flask. My buffed HP hits around 18-19k in gear. I'm not going into the mathematics of what gear to choose from this guy, but resists to 295 is still going to be king.

You can simply be gibbed as a tank (even one shotted I believe, although i've never seen a 0 resist 20k'er, only the 25% 15k'ers), but it is extraordinarily rare. Not being crit is super important first of all, so get that, then let god sort out the rest of your damage, cause its mostly uncontrollable. I didn't really dip on our kill earlier this week, so as long as you have a lot of heals incoming at any given time (nightbane, tidewalker, gruul style), you'll live through the bursts...

Shield block appears to do nothing.

Yes, though the Mark of Vashj you receive upon completing the Pens quest says otherwise:

http://thottbot.com/s39145

Hah, funny.

One raid to rule them all...

I assumed the poster did that intentionally.

I always refer to it as serpentshire (on those rare occasions that I refer to it at all) simply because the in-game inconsistency amuses me. Besides, serpentshire sounds more interesting than shrine. The game has enough shrines, temples, altars and so on already but it has not nearly enough small villages of snakes.

Yes there is. If it's elemental damage instead of physical damage they use for AUTO ATTACK melee, you can't block it. There are plenty of elementals that melee for physical damage and that can be blocked, you're right that there's no clear rule governing it and you can't tell what type of damage the elemental will AA for until you engage it.

I'm pretty sure your theory is correct.

I know for a fact the fire elementals in MC are unblockable, however the lava/rock elementals could be blocked. I very clearly remember getting smacked around by the fire elementals before I got my alt some crafted FR gear. Core hounds used physical attacks w/ a fire breath from what I remember. I'm not 100% sure about the imps, however, I'm pretty sure they were pure fire damage and also unblockable.

I don't remember if the water elemental in DM:E or the elementals in Sillithus were also unblockable, but it wouldn't surprise me.

I've always noticed this the first seconds on a mob. If you have a "proper"scrolling combat text or combat log, you can easily see if it's elemental or physical damage. If it's elemental (purple/blue damagetext for me) it's unblockable and you can't mitigate the damage. Generally from every fire/water elementals (Elemental Plateau etc), if it's physical, usually earth elementals, well, you know what happens then.

Core Hounds melee for fire damage and bite for physical damage. That's why the ones that applied a -FR debuff were so dangerous to the tank back in the day, when he had no FR and 6000hp.

Yeh there some ranged mobs in botanica they do an arcane attack. My hitsmode showed up xx hits you for 1200damage 300ish resisted 250ish blocked. Could be a bug with hitsmode of course. I dident think to double check with combat log at the time.

I think this is one of those situations that can be summarily described as:
Screenshots or it didn't happen.

In general that is the case, but there will always be exceptions (such as that arcane shot). By the way, its _very_ unlikely that something like a bug in hitsmode will cause something like that, as all Hitsmode does it collect incoming Combat Log data and present it in a different way. To fabricate "blocked" when its not actually there is something thats totally out of its scope.

Can't shield block Baron Geddon's attacks either, and he's all the way back in MC =o

In essence 250% + crushing + 25% resist = gg tank.

I dont' believe they are, although you can dodge and parry them.

Some attacks can be blocked and resisted:

"Grand Warlock Nethekurse's Shadow Cleave hits Dershivar for 158 Shadow Damage. (1307 resisted) (250 blocked)"

This is from a Fraps, from which I can't seem to extract a screenshot.

http://home.comcast.net/~vsarp/images/socwtf.jpg

I don't recall having anything crazy like this happen ever again since then. So yes, you can block and resist the same attack simultaneously, if it is a magic-based physical attack (what?).

Mobs can block "magic-based physical attacks" (physical-based magic attacks is probably a better descriptor) - ask any hunter with Arcane Shot. Players can't, as far as I know.