Guild Wars 2

So maybe some will not agree but i have issue with viper mesmers. In general main issue is condi with quite good shatter dmg and really good escapability on them. What you do with them ?

It’s certainly one of the harder matchups. I’m assuming a build with greatsword and X/shield
I like to hold shield block for their out-of-stealth bursts with clones, I tend to wait a couple seconds before using it because if they want to wait it out their stealth will run out and you can just dodge by or LoS.
Always hold rush to close larger gaps or to run or an emergency LoS if you’re about to go down, don’t be afraid to cancel rush too, it hits hard but against a Mesmer it might hit 1/100 times so I’d weapon swap as soon as you get close and go for some autos or a shield bash/headbutt, just be prepared to cancel, cleanse, or pop berserk if they avoid it or blind you.
If you really need the health don’t be afraid to use your burst on a clone, just be sure you’re not blinded.
Try not to let yourself get interrupted, keep a good peripheral awareness of the clones, especially when you’re close to the mesmer, and keep pressure on the mesmer at a constant, only drop pressure to avoid heavy damage or if you need to regen up.
A wild Arc Divider when they’re invisible if you can predict their ports/movements can REALLY wreck their plans, particularly when it outright kills clones on a solid crit, which is also why I like sigil of force, just that little bit to help nuke clones and deny shatters. Try to get Stick and Move to do some work there too, an extra 10% if you don’t have 100 endurance.
The most important thing to do is land bursts for adrenal health. If you miss one you’re in trouble, if you miss two the fight is over if it’s a respectable mesmer.

Keep in mind this is just my experience when fighting them, as far as I can tell they don’t like constant pressure, it’s a pretty situational fight like most are as a Warrior.