Group PVE Technique
In group PVE, a rogue is intended to deal damage, with crowd control and caster control being secondary aspects. When paired up with a tank, you should be able to deal massive amounts of damage with your Ambush and Backstab abilities. You can also contribute by using Sap to knock single members of enemy groups out before a fight begins, but you’ll have to quickly retreat to your tank’s positions, because any other members of the enemy group will immediately begin gunning for you. Improved Sap can be a big help here, especially in instanced dungeons, as you’ll be able to Sap a target without breaking stealth or waking up any other mobs, allowing your mages to safely Polymorph another target, thus letting you more thoroughly break up groups of mobs.
Beyond that, though, you should just concentrate on dishing out as much damage as you can, while using your special abilities to interrupt spellcasters or snare any enemies that attempt to run away.