I'm high geared playing these styles a lot at the moment w/ raddons & AOTHG. Mastery and Crit come as the best stats for ST and the optimal stat shifts towards full or nearly full Mastery (>50%) as you get more targets.
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Selecting First Blood instead of Chaos Cleave dramatically drops the weight of mastery, especially for ST. This is because Blade Dance does not scale with Mastery at all while Chaos Strike/Chaos Cleave scales strongly with it. With a decent amount of Mastery you take Chaos Cleave for both ST and AOE so make sure you're not simming with First Blood unless your Mastery % is unusually low - if you are, keep in mind that the stat that is simming better right now is not neccesarily the best stat in full gear optimized specifically for the style.
Old War prepots are losing to Prolonged Power even on single target. Nemesis can sometimes be below or around Momentum on 1 target(?) and loses to Momentum on 2+.
That should explain the comments above - being based 100% on ST damage while having these issues.
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300s +-20% ST^ SimDPS 698k. Crit sims 2.1% higher than Mastery for ST because i have more mastery than would be required to balance out ST (44-45% on this gear). It's set up that way because of scaling against different target counts.
3target cleave:
25.39 / 23.59 / 21.82 / 19.57
mastery vers crit haste
10target cleave:
122.65 / 118.30 / 114.37 / 39.46
mastery vers haste crit
Vers and Mastery are close on multi-target but that vers value is highly inflated because i have 45% mastery and only a few % vers. If it were higher then some mix of the stats would become optimal such as mastery heavy with some vers; It's not.
Crit is strong enough to justify mixing into your stats for ST and low target counts - pure Mastery will lose to a Mastery heavy mix of Mastery/Crit.