Guild Wars 2

You seem have a general idea of how to play the class based on your op so I won’t tell you which moves to use and when, but rather on how to win a fight vs a thief.

This applies to staff/sword+pistol as you’ve indicated that is what you were using.

Keep chaos armor up as often as possible while he is actively on you. You (obviously) have chaos armor as Staff #4, but you can also do this with combo fields. As explained by others above me, this is done by using staff #2 (leap combo finisher) inside an “Ethereal” combo field. Chaos Storm (Staff #5) and Null Field are good examples of ethereal fields that you can take advantage of. Having a high up-time of chaos armor against a dagger/dagger thief is an amazing advantage you can’t overlook.

Be aware of when he uses haste. Most people tend to blow their load early on so be careful of this and watch for the little foot buff! Best way to counter haste (in my experience) is to use Diversion or Distortion (default keys are F3 & F4, respectively). You can use both of these abilities while stunned, but they do require you to have clones active. If you do not have clones active, you have to resort to other parts of your tool-kit, such as blink. Also note that using haste using 100% of their endurance so he will not be able to dodge roll after you for a bit after using it. Keep this in mind and keep as much distance as possible until Haste is over.

Don’t be afraid to tango in melee range for a bit. Blurred Frenzy does a lot of damage, on top of making you immune for 2s. Try to take advantage of this when he uses a gap closer if you can (gap closers include Steal, Shadowstep, Infiltrator’s Strike, etc.). After a steal is usually their best moment to dump their initiative, if you can get them to dump it into you while you’re immune, that’s really the best case scenario.

Hope this helps.

Good Luck!