I can however say with confidence that you can actually survive the cast with the use of cloak, and this without taking any damage as expected.

When Elegon was released on HC, we tried having me soaking one of the blasts, worked the first two times but not the third. So we ditched it as it was unreliable.

I'm not totally certain when I used cloak, I know I did not aim to immune it, but rather just cover it, however this doesn't mean that I didn't use it 0.5 sec before. I'm pretty certain I did never cloak before the cast started though.

That's all info I can supply, basically, it is doable, I'm just not sure what timing is needed.

There was a blue post some time ago stating that immunities won't work for soaking.

Back when I made my original post about soaking on H Elegon the annihilation was immunable. You can see that in this log here. I take no damage from total annihilation but soaked 13 of them. Since then they have changed it and you cannot immune it.

This kinda hits home at the point I have been wondering for months now... and that is "Why are so many rogues taking leeching poison as their 'go to' talent in that tier?". I have been wondering this question since they released information on "top talent choices and would really like some feedback. I am posting here as it pertains to all rogue specs and is related to the mechanics use on almost all encounters.

I would almost always recommend elusiveness over leeching. There are several reasons for this.
1.) there is a lot of aoe damage in mop
2.) Having played a healer, imo mitigated damage>minor self healing. Leeching poison healing is meh. Some fights it can be a lot, some it isn't. Generally speaking, your minor healing done shouldn't really play a big role in whether you live or die. I can understand the shiv heal's ability to play a major role in that, but honestly, most rogues forget about it. Additionally, they things that are most likely going to kill you/need the shiv heal are things that can be feint (generally, not always). Whether or not you do more healing to yourself with leeching vs the damage reduced by feinting isn't really the question imo. The real question is WHAT damage are you reducing and WHEN. Leeching is sustained healing, but a lot of it probably comes at a time where it REALLY isn't needed. Sure, 2-4m healing done over a fight makes a difference, but being able to cut any aoe damage by 65% and any regular damage by 30% seems a lot more valuable on almost every level. For extreme examples of it's power, just go back to beta testing on lei shi where rogues could take 25-30 stacks of splash and STILL take less damage than tanks. I was solo tanking lei shi on beta better than tanks were doing while tank swapping. Feint is already pretty effing Op and this just made it better. Another: Elegon and going to 25+ stacks before resetting. Sure you can go pretty high without elusiveness, but it just extending the number a little more.
3.) Allows 65% reduction from aoe. (It doesn't stack but is multiplicative. 50% + (50% *30%) = 50% +15% = 65%)
4.) should stack with glyphed cos.
5.) with high feint uptimes you can usually mitigate as much (or more) damage than leeching heals for and the mitigated damage is most likely during more important periods from a healer pov.

Rogue, again imo, are probably the single best class for surviving fights in MoP. Elusiveness just adds more survivability, less damage, and an easier life on the healers in healing intensive timeframes.

So again I ask... why are so many people using leeching? What amazing benefit am I overlooking? What amazing mechanic am I missing?

I honestly don't even apply utility poisons most of the time because there isn't really any value.

Regardless of cos being use, you should be able feint (with elusiveness) and survive. Honestly though, I wouldn't recommend using rogues for this unless absolutely necessary.

In response to Sinnaa's question, i think the only thing that makes leeching poison so tempting is not having to do anything and receive some sort of passive healing.
I completely agree with the points brought up by Sinnaa, and elusiveness provides way more damage mitigation in comparison to the effective healing done by leeching poison.

And also the fact that it's the only utility poison that does at least something remotely useful in raids.

I mostly only take elusiveness for progression fights or if we are still having some issues on a farm boss. For the most part once the healers get used to a fight you don't really need to take the dps loss to feint anymore, so leeching provides at least some usefulness.

Unless, of course, your healers are just not very good...then I can see how elusiveness would still be a safer option.

Garalon: For subtlety, Crimson Tempest can be used when switching to a leg or when preparing to go back to the boss to prep a bleed for the next target.

Wind Lord Mel'jarak: Crimson Tempest is a dps increase over Eviscerate for subtlety rogues (maybe combat too) when adds are up as long as the bleed isn't clipped drastically. Sub rogues should make sure to use CT when the previous bleed is still up in order to get the damage bonus from SV.

Amber-Shaper Un'sok: Crimson Tempest is a dps increase when 3 mobs that are not taking reduced damage are up, and should be used when swapping targets for the bleed if Redirect isn't up.

Blade Lord Ta'yak:
He teleports everyone to the center at 20.5% HP left. Using Killing Spree after 20% will be too late.

Garalon:
If you are in a 10 man consider using Glyph of Expose Armor to provide the -12% Armor buffs on the legs.

Elegon:
Glphy of Deady Momentum did not work for me on Energy Sparks

Wind Lord Mel'jarak:
May be obvious, but anyway: switch to boss once a group of adds died as combat and cleave off the boss, since he gains a +dmg received debuff. Damage to adds will not increase but overall damage will.

All of the above are for normal mode

Edit: Useless information.

Because of the size of the Sha of Fear's hitbox Blade Flurry can be used while attacking the adds as long as they spawn in one of the closer locations to the boss.