Weapon Slot #1 Single Target
-Open up with Engulfing Flames, the fire damage buffs applies for entire group and only once so applying it quickly and keeping it up benefits entire groups dps. Simply reapply on DoT timer and maintain it.
-Light Attack/Scalding Rune, Light Attack/Unstable Flame 2-3 times in a row (quickly). Repeat.
-Spell Symmetry for magicka
-Considering Engulfing Flames is only really effective with ONE DK running it, the back up options to replace are as follows....
A. For first 3 bosses in AA: Evil Hunter. Keep the buff up during entire fight.
B. For last boss in AA: Fragmented Shield. The final burn phase has heavy damage going out to group. Spamming this constantly has the AoE blast going constantly and helps mitigate the damage for the burn phase as well. This can only be applied by 2 DK's. Any more than that and the shield is simply replaced by next caster and the damage is not going out without the explosion aspect of it.
C. Flames of Oblivion. This one is to be used carefully. The fact that it is a steady magicka drain means you will be using Spell Symmetry for magicka alot and thereby having health drops. If you are running with experienced healers and know fights well enough not to over use Spell Symmetry or use at wrong time, then this is extremely viable.
D. Crushing Shock: This works really well in Hel-Ra where you will need the interrupt for adds.
E. Elemental Drain: Again, like Engulfing Flames, this is only most effective if ONE person maintains the debuff.
-Concerning the Light Attack/Unstable Flames 2-3 times part: Unstable Flames builds in damage output over the time of the DoT. However, the building of the DoT maintains its peak damage output as long as the DoT never wears off. Also to note, this ability is extremely cheap to cast. So you are effectively using it as more of a damage hit rather then simply maintaining the DoT. In other words, you are not waiting for timer to refresh it, but rather using it as a regular hit in rotation. The object is to get x3 light attack/Unstable flame combos in between having to recast the Rune, but x2 is more than acceptable.
-Just to reiterate on Runes: Volcanic runes is NOT to be used in Trials, but rather Scalding Rune.
Weapon Slot #2 AoE
-Drop Cinder Storm and Spam Elemental Ring, simple enough
-Notice the "Empty Slot". Most of the time you are going to want to use Chains here. Pulling in healers and ranged for the AoE stack and burn is extremely useful. Flames of Oblivion would be excellent choice if chain pulls is covered and/or not needed.
-Particular to the 2nd boss fight in AA: use Annulment in empty slot. You will need that for her AoE blast, everyone will need it actually 
.
-Other options for "Empty Slot" could be pretty much anything with DoTs/AoE. Engulfing Flames, Dark Talons, Unstable Wall of Flames.....all decent choices.
-Having this as your second bar setup works well in fights like 4th boss in AA where you have a AoE adds/trash mobs that transitions straight into a single target fight without leaving combat. Also, in terms of timers, this will eliminate the need for pausing for hotbar switches.
Ultimates: This guy likes to use Corrosive Armor, but that is not at all essential or must have. Flawless Dawnbreaker is worthy here as well as it gives weapon damage bonus and the Elemental Ring is in fact weapon damage. Unstable Wall of Flames is in fact weapon damage also, so if you are running that in emply slot then it's even more of an advantage. You definitely want Standard of Might. Oppositely, you could run the Dawnbreaker on single target bar and Standard on AoE bar. This can benefit because of the amount of light attacks you are doing and you simply have to swap bars to pop the Standard when you want it.
Feel free to ask me anything on this, I have been schooled pretty well up to this point. This is much more comprehensive then the original post theory. Hope you enjoy 
