You mix up two things again. Most of what you describe as useful Intervene is about Intervene, not about Safeguard. At least that is what I read into your example of intervening a healer. And I don't get why you want to do it at all. Since you zoom out of melee range, so you cannot build up threat on them at least for 2 GCDs. The healer should not pull aggro anyway, if you are oping up correctly and I don't see how it is easier to grap losing adds if you do move out of their range. If you stay where you are, you can ensure the adds targeting you (and not your melee for example) much better, so your healer will not be in danger, anyway.
One problem with your examples is that it's hard to know who will need the buff in the near future. I'm playing a holy/disc-priest as former main and current alt. I know about the difficulty to decide when it's the best time to apply dmg saving buffs to which "normal" raid member. At least you need to communicate your buff well, so that healers know that the person can be ignored a little bit and that the person saved does not spend the one GS at the same moment.
Actually, you just didn't get the point I was pointing at. I'll reprahse it - Intervene doesn't work on magic damage that bosses throw around. Safeguard's buff of 5 seconds does. There is no damage reduction buff without safeguard. Usually, there's no point interving anyone [unless you need the movment or he's really high on threat] without safeguard, except maybe the other tank to soak a hit for him in a very few situations. WITH the 2/2 in safeguard, the ability actually gives 30% reduced damage to the target you intervene - hence is worth casting on anyone as often you can, even if to just reduce the aoe damage he takes by 30% for 5 secs.
Originally Posted by Katzazi
About Chogall: When I'm thinking about a utility build for this encounter, PH and Gag Order (to free people with Heroic Throw) would come into mind way before Safeguard. Sure healing is hard pressed in p2 and if someone reaches 100 corruption the only thing that prevents their death is dmg reduction, not healing. But nobody should get as high, while you should need slow in any case. (You can use Intervene / Jump to get near the ooze and away from them.) Btw: When someone is as high that they need Safeguard to survive, they have to puke often enough. You often enough don't know exactly where you will land with Intervene, so you may just rush into the puking - giving the healers even more corruption stacks to heal against.
Tbh, I just shockwave people and it works just fine. If you'd have to respecc, your choices would prolly make sence [even tho PH is only good for add slowing, and we usually have a hunter/boomkin taking care of those], but I don't respec for each encounter unless it's progression run and my utility is just extreamly needed.
I don't think the usfullness of those 2 is that significant, unlike the usfullness of safeguard.
Originally Posted by Katzazi
The question is not: Can Safeguard be useful? (All talents available can be useful.) But: Are other talents (which compete for the same talent points) more useful for the encounter in question, if Safeguard may be used for that encounter at all?
I don't think all talents can be usfull, take a look at blood craze for example. I do think that Safe Guard is a VERY usfull talent in the right hands, even tho it can easliy be neglected. I've tried to think of other places I'd want those 2 points in, and except maybe putting 2/2 in imp. revange for the aoe damage, I really don't see anything that can come close to it.