Hey all! Let me preface this by saying that I do NOT have a good DK character; my highest is level 60. That said, I have way too much time on my hands and thought I would give you a heads-up on the use of Army of the Dead. Most of you will probably know this, but some might not, so I thought I'd give you a second look at an underused spell.
Army of the Dead is primarily used defensively; it's on a 20 minute cooldown (usually) and used as an "Oh Sh*t" button if a tank dies or you get an extra pat. But some fun facts make your ghouls even cooler.
1. Army of the Dead will NOT taunt raid bosses
Again, most people know this. But this means you should be using AotD wherever it would be a DPS boost while raiding. The cooldown isn't short, but it isn't too long either, especially when raids last a couple of hours. The best boss to use this is, of course, Patchwerk. Other good bosses are Loatheb, Gluth, Maexxna, and (assuming you can place them well) Anub'Rhekan. If you move quick enough you can also use them on Thaddius right after you jump and before he's active (no use doing it during the fight, as you'll do more damage just by attacking for 6 seconds). Some parses on the EJ forums showed these ghouls being as much as 10-20% of the DK's DPS over the course of a fight.
Be warned, they WILL taunt anything that is not a Skull for a level. This includes the adds on KT, adds in Sartharion + drakes, slimes on Grobb (if they live that long anyway), zombie chow on Gluth (if they get close enough).
2. Army of the Dead is an extra mitigation cooldown for tanks
Again, I realize this is obvious for most people as it says this right in the tooltip, but I think a lot of people forget it too. Most tanking DKs will have 40-50% combined dodge and parry, which makes those 6 seconds an equivalent damage reduction. The best time to use this is probably on Sartharion with drakes (or hell, without) to mitigate one of the breaths. I imagine it might be worthwhile on Malygos as well, for the same reason, although not attacking for 6 seconds might be a waste if your raid's DPS is strong while sparked.
3. AotD benefits from AP boosts and haste at the time of casting.
The scaling on AP is VERY poor. You'd see maybe a 10% increase in their damage if you added 2k AP for the summon. Haste, on the other hand, scales pretty well. If you managed to get 50% haste, their damage goes up almost 30%. The numbers I am quoting is from this post: http://elitistjerks.com/1071066-post66.html
Note that haste does NOT make the summoning portion speed up, and it will NOT summon additional ghouls.
4. Dancing Rune Weapon will summon Army of the Dead as well
However, I'm not sure how useful this might be; it is arguable that you'd do more damage by attacking while DRW is up instead of summoning. Also, the DRW ghouls will die as soon as DRW ends.
Ok, that's all for now. Sorry if I stated the obvious, but I know out of 4 DKs in my guild I have seen AotD used MAYBE 3 times over the past few weeks. So I'm trying to spread the word.