I was trying to wade through the other demo shout discussions and found a lot of it confusing, contradicting, and off topic so I figured I'd ask in a new one. Does AP debuffs have a limit or cap that makes improved demo shout useless in pve. Some of the posts I read said that 300 seems to be the cap, but I am hoping for some data in support or against this theory.
I don't remember the exact numbers but there was definitely a thread awhile ago, I believe they said demo was about a 16% reduction in damage and improved demo was like 22-23% reduction or something?
Theres always been an argument as to whether you can 0 out mob attack power just leaving them with base weapon damage, or as to whether it just works out to a % reduction across the board.
Exact numbers aside, Improved demo definitely makes raidbosses hit me for noticibly less then regular demo, meaning a few hundred points of damage per hit on stuff like Morogrim and Vashj. If you can dig up that thread, people were trying demo on lower level creatures, comparing the reductions. The finite thing that was concluded is that you cannot 0 out a monster's damage, but if I remember right people were showing a 16% damage reduction from max rank demo untalented at all levels?
I'm sure someone can dig up a direct link for you.
i remember there was a thread with all -ap debuffs/buffs listed with their % reduction on equal and boss mobs. iirc having both imp demo and a owls screech was pointless (unless curse of recklessness was used afaik).
There is a cap of the effect at 30%. I have more uninteresting data of in-between levels (24-26 and 52-60) that all show that the %reduction of all effects combined cannot go above 30%...
...Imp demoralizing shout is pretty huge. The -atk effects are linear (I tested this when testing the interpolation method), which means the dps loss is sizeable on any mob in which the cap does not play a role. For example a mob with 18% reduction via demo would have a 25% reduction with imp demo, that's kinda a big difference. I guess we knew this too, but again, not terribly widely known.
It seems the numerical AP reduction is hard to relate to the exact DPS reduction since mobs all have different base AP/weapon damage/multipliers and so on. However for mobs of the same level it always appears to reduce the damage by the same percentage. Also, there are some boss abilities like Mortal/Unbalancing Strike that are affected by AP reductions and some like Patchwerk's Hateful strike that aren't.
Even 5/5 Improved Demoralizing Shout doesn't get you to the 30% cap against any mob that is close to your own level. In the tests a same-level mob lost about 25% damage from 5/5 Improved Demoralizing Shout. So having a 5/5 Imp. Demo warrior in your raid is very much worth it. Since thunderclap was improved in the patch it's probably well worth having somebody with Imp. Thunderclap too.
According to tests with Beast Lore in Curse of Weakness you only really benefit from Improved DS in BC if you also apply Curse of Recklessness. Tested on, as I recall, Outland beasts ranging from raptors in Blade's Edge, through Uvuros in Shadowmoon and finally the Lurker Below in Serpentshrine; all these were capped at around 315 AP reduction. The working theory was that this is simply because mobs don't have any more than 315 AP to reduce.
It's also possible that non-beasts have more AP than beasts.
Note that this makes improved demoralsing shout one of the best dps talents a dps warrior can take, assuming three warlocks, imp demp allows you to apply CoE/CoS/CoR as the standard curse array with no downside.. and CoR is a very, very good curse for all physical dps.
I was thinking of picking up improved CoW for my tanks, so they wouldn't have to use rage and waste a global cooldown every 30 seconds keeping Demo Shout up. It's a 2 minute curse for me, so it's very easy to keep up. Considering that our usual offtank is a druid and that our MT doesn't have improved Demo Shout at the moment, how much would this help our tank? As a caster, it's hard for me to judge how much of a difference a 120 AP reduction would make. Of course CoS/CoE/CoR are already being taken care of.
Just for the record,
CoW = 350 AP reduction
Improved CoW = 420 AP reduction, same as Improved Demo Shout.
Assuming that it's a linear effect, CoR is used and that a 300 AP reduction gives 14.24% damage reduction as per the CoW thread linked above: using Improved CoW over a regular Demoshout means going from 92.16% of regular, non-debuffed damage to 86.72%. This is a 6.18% reduction in melee damage taken. Very good returns for 2 meagre TP, beats every single warrior mitigation talent save Improved Shield Block.
If ever you get a hunter with a bird pet for Screech or a warrior with Imp. DS - or if ever you don't have the 'locks for CoR - then the benefits from Imp. CoW will lessen considerably, but until then I'd definitely recommend it.