PvE – Thieves are the highest skill cap class in the game. If you master your movement, dodges, leaps and stealth, there are few players who will be able to catch you. Remember though, if you’re the kind of player who likes to pull up to a monster, sit still, and fight it out, you’re going to have a bad time.
Make sure to get either two pistols or a short-bow as soon as you can. These are going to be part of your rotation by level seven at the latest. Though lower on damage than daggers or sword skills, ranged combat is a vital part of thieves’ language of death.
Don’t assume that power is your only route to deal damage. Thieves want a very high critical rate AND condition damage. You have access to plenty of Poison and Bleeding effects, and it’s just pants on the head stupid to ignore them.
When you start fights, you should open with condition damage and then move on to direct attacks. Thieves don’t have cool down problems, but they do have to worry about running out of ‘Initiative’ in extended fights.
Try to expend all your skills in a way so that they have the most effect. Whenever you’re stealthed, move around to the back of the enemy to backstab them for an insane amount of damage (be careful not to reset the mob if you’re flying solo).
Use Death blossom just as the enemy is about to attack, mitigating damage. The thief has light armor so most of his survivability comes from not taking the attack at all. Most importantly, make use of your mobility.
PvP – Thieves are masters of the PvP environment. Their traps and venom are frequently effective against opponents. You get to start fights when and where you want (due to Stealth and the nature of traps).
Through high mobility, you can guard areas well and push forward toward new targets at high speed. Avoid long and drawn-out battles when on the offense. Keep in mind that you can disengage from a fight and reengage quite quickly.
When defending, load up on slot skills that let you draw out the encounters. Bring a ranged weapon, such as double pistols, and make the fights last for an eternity.
Kite enemies, Shadowstep away from them if you get Stunned, and use Stealth and barriers that break line of sight to constantly force enemies to chase you without getting anything done. This gives your allies time to swing by and mop up the attackers you’re kiting.
Finally remember to use Heartseeker on weakened enemies, it’s a truly devastating skill when the opponent is at 30% hp.
If you want a more comprehensive guide on builds for the Thief for Dungeons, PvP or PvE, check out our Thief build guide.