What part of Legion Destruction is complex? I'm just not really seeing it. I'm not saying it is going to be easy being among the best, assuming equal gear, but I strongly believe that the difference between good and bad destruction warlocks will come down to talent choices, gear, and perhaps artifact traits. There are almost no complex interactions between skills, perhaps with the exception of havoc'd channel demonfire, since it is not necessarily intuitive that you should or should not apply immolate to the secondary target depending on how long it will live.
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I think people are referring to Legion because it is what we just had. MoP and WoD Destro were very similar though.