I was about to post this in the healing compendium as part of the discussion of divine aegis stacking, but that discussion is getting too multi-threaded and big so I decided to create a new thread to discuss this particular problem.

Blizzard says that they can't let Divine Aegis stack because it would create "crazy" situations. This sounded ridiculous to me, so I did a bunch if calculations to see exactly how crazy it could get. I am intentionally trying to stack this situation to make Divine Aegis as overpowered as possible because the point is to show that it will never be. The craziest situation I can think of is one where a shield gets so big that a boss can't even do damage to the tank.

Since I'm in 10-man gear, I borrowed some stats from a better geared priest from the armory. Counting in raid buffs, a discipline priest might look like this: 1470 int, 1240 spirit (normally not great for a discipline priest, but has a useful application in this particular situation), 2260 spell power, 27% crit chance, about 30 extra mp5.

This means that with a grace stack (which will come quite quickly), a penance hits for about 9300, a flash heal for about 4200. The priest has 25633 mana, regens 102.1 mana per second (510.5 mp5) while casting with a mana spring totem, and 705.7 mana per second (3528.5 mp5) while drinking.

Stacking up massive shields must be done on select targets, so this will not be abusive against raid damage. I decided to use Patchwerk as a model, because he will only hit two targets (if the off-tank never loses health, he'll never hit a second off-tank). Looking at some WWS logs it looks like he is going to do about 3 million damage over the course of the fight, approximately half of it to each tank. Lets say we bring two DK tanks with bone armor (never getting hit means never losing charges, so 40% less damage the whole fight). Now we've only got 1.8 million damage of shields to put up before the fight.

We bring along six discipline priests geared as above and have them start putting shields on the tanks. Lets say they have enough haste that they have a perfect penance, FH x5 rotation every eight seconds (about 18%, which is easy enough to do). Assuming Imp. Healing and the Glyph of FH, this costs 3735 mana, which is 466.875 mana per second. Less regen while casting is 362.775 per second, meaning it takes them 70.3 seconds to run out of mana. Note they get no rapture mana as the target is at full health and they do not get replenishment unless there is an endless supply of rats for the ret paladin to judge. It takes them about 36.3 second to drink to full mana, which means they spend just under 2/3 of the time casting if they cast - drink - cast - drink. We'll call it 2/3, meaning 4 of the six priests are casting at any given time.

How big a shield do they actually put on the tank? Every 8 seconds of casting each priest pumps 9300 + 4200 x5 healing into the tank for 30300 healing. If that crits its 45450 healing which delivers 13635 worth of shield. Times the crit chance is 3703, or a whopping 462 points of shield per second. Since there are two tanks, with half the priests on each, this is 924 points of shield per second. To put a 1.8 million shield on a tank would take 1944 seconds, or just over 32 minutes. Remember that through the fight the priests have to keep casting constantly to make sure the shield doesn't fall off, so you don't even save on healers. You could have killed patchwerk sixteen times instead of going through this ridiculous exercise.

I am bouyed by the apparent fact that people actually convinced armor was too powerful for druids, and that maybe with math we can actually show that divine aegis stacking will never get crazy, unless "crazy" is to refer to the crazy people who would try to abuse it instead of just playing the game, which would be far more profitable.

What other sorts of situations would we have to model to show that this kind of stacking is really abusable?

The situation I immediately thought of was that you could pre-load a tank with a huge shield, have innervate cast on you, and keep the shield up throughout a whole fight.

Assuming the 25633 mana, and assuming that I am just spamming Penance and FH x 5, I can put up a 100k+ damage shield on the main tank (would have to be pally or DK, since rage generation is going to be nill). Once my mana runs out, pop innervate on me, I can just cast enough flash heals to keep the shield on, and then we start the fight when I reach a reasonable mana percentage.

I think the two downsides to this would be:

1) Totally overpowered for fights where the tank takes steady damage or very little damage.
2) Forces you to have a tank that uses mana or runes.

Thats why it won't happen.

We should admit that Divine Aegis, with his current mechanics should be exploited if it was stacking. Anyway, as said by "l337n00b" it would require a lot of preparation to do it ... in fact, as much time than you need to make a bunch of try and on a very specific fight where you can bring 6 disc priests without any danger.

But let's say Blizzard politic is "no exploit at all". So, a suggestion I would make to them (maybe a US poster here can do it for me) is to allow Divine Aegis to stack, but taking in account only 30% of the effective healing instead of overheal as actual. With this simple solution, we get, in my opinion, a very good compromise without any possibility to cheat.

I disagree that I am making Blizzard's point for them. The case I gave was very extreme and even in that case stacking shields became nothing but a waste of time.

Blizzard has already stated that they have no interest in balancing the game to account for the top end, cutting edge raiding guilds because it is simply impossible for them to create encounters that challenge these guilds and are accessible to a larger player base. What other kind of guild could muster the required priests to effect such an abuse? And these guilds wouldn't even have an interest in doing this because it's no way to get world firsts. As gear gets better the amount of damage you need to stack will increase as well, and bone shield is already getting nerfed. You use an hour stacking a shield on your tank while the other guild uses the hour to learn the fight. Since most fights are not tank-and-spank, the shield is not going to make you win by itself.

How much time it takes to do things is a seriously consideration in whether they are abusive. Suppose we found a clever combination abilities that let us solo a raid encounter with a near 100% chance of success. That sounds like a problem on its face, but whether it is a problem or not does depend (among other things) on how long this will take. If it will take 80 hours of game play to accomplish then it's not really a big problem at all. The clever people can do it just to show it can be done and then go back to their guild where they get loot faster by playing as part of a team.

There are however methods to avoid such a thing. Restrictions such as not being able to absorb more than half your health or the targets health or some sort.

Divine Aegis not stacking really weakens several of the Discipline Talents and seems counter-intuitive to the multi-hit format of Penance.

At the very lease, DA's procced by the same "cast" of Penance should stack with it self, in my opinion.

It would seem the tech for this is already in the game, as Lightwell healing effect is broken on a percentage of life.

I'm sort of at a loss though for the purpose of the thread. I was under the impression that blizzard suggestions were frowned upon here.

Yeah, I actually got the idea form the Paladin Talent "Eye for an Eye". So the tech is certainly there.

Its been stated that next build DA will be stacking with PWS. With Disc talents you will be able to get A LOT of mitigation on a tank. A PWS stacked with a DA is A LOT of mitigation.

See the compendium thread for more details where it has been discussed already.

Some interesting scenarios are created here, however, I´m afraid many of them are far from reality.

Firstly, arena is non-issue since every buff running shorter than 30 seconds is removed after the preparation time.

Secondly, the Penance+FH shield stacking would be possible, however, to which benefit? I don´t need such a shield in a situation where the tank takes low damage and in a case where he takes high damage removing even 100k Aegis would be a matter of short time. A typical boss fight lasts longer than 15 - 20 seconds, even if you could make your tank near-invulnerable for such a time it wouldn´t be much different from a Shield Wall (with the added 'perk' that it´s highly uncomfortable to get such a shield running since it needs a lot of time). Also, you could only have it at the beginning of a fight which is normally the time at which you need the least healing at all.

Anyways, as I already said in the Healing Compendium, be honest: It´s not such a big deal many make out of it. With the next patch Aegis will stack with PW:S which is probably more important than stacking with itself. The only really affected spell by not-stacking Aegis is Penance and I can live with this, since if Penance crits multiple times I´ll be unlikely to really need the extra throughput (though, it would be nice, no question).

One easy way to prevent most exploits is to make Divine Aegis work only while in combat, and be removed when combat fades.

It would seem that the priest lobbying for the stacking of Divine Aegis have forgotten, or haven't heard about rolling ignites. I recomend a google search regarding this.


edit:
link from the original level 60 Naxx with rolling ignites:
Thaddius 28.6K rolling ignite