A very nice write up.
To add my personal takes as feedback to Blizzard:
Desecrate:
What is the purpose here? Is this intended to be a button you push when the tank and/or mechanics move targets out of DnD? Or is it intended to be a drop and immediately detonate?
Just reading the description it looks like the best option is to detonate instantly, to get the 150% modifier on all the damage. Of course that assumes the “Grants you the benefits of standing in Death and Decay” is for the same duration as you would have in a full DnD. If that is the case, why is it two buttons? Aren’t we trying to reduce wasted extra buttons? If this is a burst option to address movement, why not just have it be a single button? If not, when do you see the detonation happening. Because you can’t really balance this. Depending on how long the ‘effect of DnD’ persists there will always be an ideal time to press it, and tank/environmental/mechanics/etc. will always cause a dps loss. And worse will require non-intuitive theory crafting to find the exact best time to press it, that most player wont know AND will require mod timers to track.
And that is before we even touch on its damage balance against defile.
Legion of Souls:
Again, what is the purpose here? This effectively creates a THREE WAY choice node(that just happens to cost 2 points). What role is Legion of Souls supposed to fill? What role is Abom? What role is Army? Best case scenario of balancing is one is the best single target and one is the best AE. And that means the 3rd might as well not even exist, other than as a trap for players not up to date on theory crafting. Worst case, we don’t take any (subtlety looks at our current M+ spec). There is no good solution to this 3 way choice.
And, on Legion of Souls, why is this not the DnD replacement option? Honestly, this skill basically reads like DnD. Shadow damage to all enemies in a radius over time. This is really just a DnD that follows the player. Reduce its CD to the same as DnD, add the DnD benefits to the spell, and make it the choice node with defile instead of Desecrate. IF you then also want to let players detonate as a burst option you can. But it can be balanced around just being a DnD replacement that follows the player. Balance its damage so defile is slightly more damage at the cost of mobility and you would have an actual choice.
Then you can do what you always should with Army and Abom and make it a choice node instead of requiring 1 point for Army and then another point to replace it.
Which of course leads to the whole Dark Transformation:
Why are we doing this again? Why are we required to pick up one talent to then replace it with a second talent?
I can see the argument for making it one button. I don’t believe that is needed. But, if you feel it needs to happen just make it a single talent. If you want to just remove the Dark Transformation and let Apocalypse just be its thing, just do that. If you want players to choose between them, just make it a choice node. There is no reason to have a 2nd talent replace another one that is also taken.
IF you want to reduce an extra button in the ramp up, merging Unholy Assault with Apocalypse would be a FAR better option. And again, as a single talent.