hey this is my first attempt at writing a guide so go easy <3
I also searched for "Mount hyjal trash" and found no results.
As anyone who has been into Mount Hyjal will know, the trash is a bitch, you need to make sure you are doing your bit and getting the most out of all of your possible damage at all time. Unlike any other instance it is crucial that trash goes well inorder to have the best possible chance against the end trash boss.
From a rogue perspective the most important thing is focused fire. Next to that is SnD(Slice and Dice)/R(Rupture)/Evis(Eviscerate) then using your CD's. I'll go into greater detail for each of these seperately.
Focused fire: Make sure you have 1 person who is marking out a focus fire target with a skull, and ALSO a person who can be set as Main Assist. These 2 things are crucial. As the skull is not always easily spotted and other times the Main Assist may be dead or not selected anyone. When we are a rogue capable of high outputs of DPS the difference between arriving at your target in 3secs compare to 10sec can be huge, averaging 1000dps plus 7 second would allow you to gain more points towards renewing your SnD and just generally getting each target down faster. So be quick from target to target and stay switched on with a skull and a Main Assist it should be easy.
R/Evis: Choosing how to spend your combo points is something that shouldn't be taken lightly just because this is "Trash" as previously explained. Unlike a boss fight R isn't always the the best option and in most cases it's the worst option. This is a DoT, and it is only more effective than an Evis if given the time to complete it's full allocated "Tick" time. So if your target has got 10% health and it's the focus target if you have 5 points using a R is pointless. It will be dead within 2-3 seconds of recieving the DoT anyway. But an Evisc while not dealing as much damage as a fully ticket R, In this situation will apply more damage to the target and from what i have found even when the target has 100% health when i have started on it after refeshing my SnD and then gaining another 5 points to perform a R, the target Health is too low for this to be effective anyway.
SnD: This is obviously Crucial as it increases a rogue's damage output significantly. And just like on a boss fight it is absolutely crucial that this is up AT ALL TIMES. And given that Each mob doesn't last as long as a boss does choosing how many points you want to dedicate to your chosen ability (SnD/R/Evis) is very important, Nothing should die with points un-spent on them. That being said. You shouldn't waste your points just for the sake of using them. Micro-manage each mob you attack, working out a rough idea of how many points you think you will get and what would be the best way to spend them. Always be aware of how much time you have left on your SnD. I personally have found (and please feel free to correct me or add anything) that most effective way to start and end anyway wave of trash is with a 5 point SnD, here is how i achieve that. The first target at the start of the wave, get 1 or points on them ASAP then SnD (i have 2 sec T4 bonus, not that it makes much difference, would still do the same thing if i didn't) then on that same mob i attempt to get another 5 points up and perform another SnD. This will mean that on my next target i can generally use all of the points i gain on R or Evis, not having to refresh SnD until the mob after that one. And as for the last mob of the wave, try to get 5 points up ASAP (before it dies, whole raid will be focused on it now remember) and hold them until the mob is as close to dead as your dare. Then use SnD this way hopefully by the time the next wave arrives i still have SnD up maximising my Damage output and meaning that i don't have to start again.
Trinkets/CD's: This is VERY important, secondly only to Targetting IMO. And it's Very Simple... DON'T BE BAD. Use your CD's. Get an idea as to how long it takes to clear the trash so you have an idea as to what CD's you can pop without wasting any time waiting for them when the boss arrives (For me this only applies for Adrenaline Rush). The 2min CD's should be being popped every was regardless. where-ever possible use Blade Flurry on targets you know will be targeted one after the other to minimise uptime on mobs. I also use currently Bloodlust Trinket, Any trinket similar to this should be used at the same time at Blade Flurry (again whereever possible) but having them going at the same time is not the same as having them going seperately as you are doing damage to 2 target with Blade Flurry, so you are effectively increasing your AP on both targets make you more effective and hit harder on both targets maximising your DPS. Adrenaline Rush is very handy, and should be used. Right up until the last wave. Each wave is long enough that you should be able to use it 2 -3 times before the boss arrives. Downs mobs quickly is crucial so use everything at your disposal. But also make sure everything is CD by the time the boss arrives where-ever possible.
Also, on a final note. DON'T BE BAD, Use Evasion... Use Vanish. They are Handy and help with NOT DYING. Where ever you are alive it is worth the 20 copper or whatever it is for reagent as opposed to being dead...
This was my first real "post" i have done. Be Gentle... lol