Since we already got a thread for hc talents, I thought I'd just share, what talents/trinkets i used in mythic progression.
Assault: Chi Burst, rest is ffa, depending on whether you wanna focus adds down or mindlessly cleave them to appear on top of the meter, you decide.
Reaver: Chi Wave, Xuen, Serenity, Chi Brew, soul cap/class trinket
Kormrok: Chi Burst, Xuen, Serenity, Chi Brew, class trinket/soul cap/mirror otb (depending on whether you lack hand dmg or not)
Council: Chi Burst, Xuen, Serenity, Chi Brew, class trinket/soul cap/mirror otb
Kilrogg: Chi Burst, Xuen, Serenity, Chi Brew, class trinket/soul cap (mirror otb when you go down or just want a safe option)
Gorefiend: Chi Burst, Xuen, Serenity, Chi Brew, class trinket/malicious censer (DONT use soul cap, your gonna have to get ppl out of his stomach and a proc will probably need to get canceled...)
Iskar: Chi Burst, Xuen/RJW, Chi Explo, Ascension, mirror otb//class trinket/soul cap (chi explo can carry the raid in intermissions; dont know about rjw, not really needed to kill off the small adds...)
Socrethar: do what you want, this boss is easier than heroic, just dont mess your kick up!
Zakuun: Chi Wave, Xuen, Serenity, Chi Brew, class trinket/soul cap (pretty straight forward, try to keep diffuse and zen med for soaking in p3)
Xhul'horac: Chi Burst, RJW, Chi Explo, Ascension, mirror otb/class trink/MC (RJW is OP, since your gonna have 3 adds up all the time at some point, just kick and kill all the imps ^.^)
Tyrant: Chi Burst, Xuen, Chi Explo, Ascension, class trink/MC (depending on if you really need the boss dmg in p2, switch to serenity, but the boss dmg gain will be minor, whilst not doing any dmg to the add; soul cap and mirror otb unusable on this fight, since they are baseline useless in p3)
Mannoroth: have been playing tank for the most part but heres what i found out from my few tries as dps... Chi Burst, Xuen and mirror otb are a must have; Chi Explo pulls ahead in p1 and p2, since your gonna constantly have doom lords/infernals up to cleave, I'd probably go with serenity, just for the sake of making phase 3 easier and your also not gonna be cleaving as much in later phases.
Archimonde: still testing, Chi Explo seems to pull ahead dmg wise and will also be better in p2, dont know anything about p3 and may end up playing serenity, just for more focus dmg; for trinkets im mostly using the class trinket and mirror otb
As a general info: I seem to consistantly have more succes with Chi explo, when im using the class trinket, even though it is simmed lower than e.g. MC.
Maybe something is bugged with the simulations, since (at least in the beginning) it wasnt supposed to procc your 2 piece.
I also never used something else than diffuse magic this tier and couldnt think of a fight, where dampen harm would be better.