Making a list as I find stuff. Most of this is going to be for you since you play the same spec as I.
- Druid should use heart of the wild and just dps on the pull.
- Disc priest can do > half a million damage with glyph of reflective shield.
- Combat sucks on Butcher
- If they're going to play combat they should at least play with marked for death. It's better than anticipation, which gives almost nothing, even on Patchwerk. On Butcher there is plenty of adds to exploit.
- As subtlety you should use subterfuge with glyph of vanish.
- Having assassination offspec for vendetta on the pull is significant.
- The opener you are using now is lacking. No slice and dice for the first 5 seconds and no rupture for the shadow reflection. Premed -> snd -> garrote -> cooldowns. Continue as usual.
- You're casting feint way too much. Unless you have talented elusiveness you should stop casting it completely. If you're set on using elusiveness and feint that much you should at least glyph it for increased duration (instead of cloak glyph). You should also start tracking it so that you don't override it before it's over.
- Recuperate is not worth it. Higher dps also reduces the healing required. (Maybe when glyphed, but there are too many mandatory glyphs for that.)
- You want to use your second potion together with shadow reflection/dance/trinket. It seems like you're saving it for the 2nd heroism. (Which you're not getting.)
- You're spending your energy as soon as you got it, which is the direct opposite of what you want to do. You want to start your cooldowns with an almost full energy bar. This is reflected in the number of ambushes you get off.
- Shadowstep can be used on a friendly target on knockback.
- You sometimes overlap rupture around the 3-min mark. I believe this is your reflections rupture intefering with your GUI making it seem like rupture is falling off. Also make sure you don't spam it so much that you cast a new rupture right after you applied it.
- 2 minute cooldowns should be saved for frenzy, as you can only use them twice in the fight anyway. For you this means that you use SR+coin+potion on the 4th dance instead of 3rd. Only a few people saved 2nd potion for frenzy.