Enemy Thief porting in and out of closed Quentin Lake while being invisible

[TheQuickFox.3826]

I ran around blasting fire for 5 mins and I just hit thin air. And when buff of the lord was gone the enemy Thief ported a bunch of enemy players back in to take tower. Tower was closed all the time.

How do I defend against this as Elementalist? Did I do something wrong?

[Yasai.3549]

https://wiki.guildwars2.com/wiki/Target_Painter_TrapPlace this where yu think the Thief would hide.

If yu have Arrow Cart mastery maxed, yu can shower the area with Reveal arrows.

[saerni.2584]

If you know a thief is doing this get a friend to help. Trying to 1v1 reveal and force a thief out of the tower may work but it's a bit risky because they will more easily avoid you as a single person and are going to be able to port back inside fairly easily even if pushed out of the tower. Having more target painters at least helps force them into at least one trap and then they will need to run out of tower, and maybe not be able to return depending on timing.

Having a partner with AoE reveal skills is also helpful (as is the suggestion to use an Arrow Cart if that option is unlocked).

Another option is, as a scout, forgetting the thief and focusing on the people coming to take the port. You can get your allies to come save the tower if you can say in chat "15 XYZ through frogs to QL." If your side responds quickly (hopefully with being close to keep), the thief will have wasted their time. Or, if your side doesn't respond then the tower would have been lost even without that thief so it won't matter that the thief was there the whole time.