I used to run a 30/25/10/0/5 trait spread.
30 into Power gave me +20% Mind Wrack, -20% GS CD, +50 power wielding Greatsword, +15% more damage from illusions. It also gave me +30% condition duration, and +300 Power, both of which were beautiful and help a lot since…
25 into Dueling gave me +1s of Vigor on crits for extra dodging, passive Phantasm Fury for +20% crit chance on my Berserkers, the ability to inflict bleed on my targets when my illusions crit, and an increased blink range for getting the kitten out of dodge.
10 into Chaos was utility. It gave me a little more toughness, a little longer boon duration, and a passive regen at 75% HP. The real perk here is the Descent Into Madness trait, that reduces fall damage by 50% and causes a Chaos Storm on impact. Great for dive bombing enemies off walls, and occasionally will give you free swiftness/vigor/regen what not when you land hard.
then 5 into Illusions for the -20% Illusion skill CD trait, bringing my GS 2 and 4 skills down by quite a bit.
Note: My berserkers were getting a massive power boost from my 30 in Domination, and crit a lot due to passive fury, which meant they regularly stacked AoE bleed AND cripple while dealing awesome damage, with a -20% CD thanks to Domination’s GS trait. That trait, plus the illusions trait, made them somewhat spammable, and turned GS2 into a legitimately useful skill that could clean HP and give you a free shatter, while simultaneously stacking might/vulnerability.
Utility Skills were generally something like Blink/Feedback/Null Field.
You’re really squishy with this set up, but since GS is an extremely long range weapon, and your phantasms are doing most of the crowd work for you, this just means you should never try and get up in someone’s face. If they try, GS5 to knock them back, then blink right the hell away – A 1200 range teleport is generally enough to escape someone who just got knocked back and is crippled.
Feedback is the best WvW skill. It screws up ballista, it murders all the ranged kitten, it can be used offensively AND defensively, by negating their attacks towards you, and reflecting them back wholesale at them.
This build regularly let me harass walls with impunity (iBerserker, long range GS1, Feedback), and harass FROM walls to great effect (iBerserker, long range GS1, feedback, MindStab on sieges/melees at a gate, Mirror Blade + F2 for confusion lulz anywhere)
And even in Zerg vs Zerg, I felt I could make a difference by supporting my allies with cleansing fields (null Field), protecting and breaking up focus firing ranged players (feedback on them, or on wounded allies), and generally just shaving HP down and preventing the enemy zerg from either running to safety or chasing us down successfully (iBerserker buzzsaws through everyone and AoE cripple/bleeds)
If I occasionally got targeted, I’d dodge roll once, then blink to the back lines. They tend to switch targets quick, rather than follow, so I could go right back into the fray.
The glaring problem with this, though, is that you suck at surviving damage. You have no HP – I think my Max was like 14-15k or so. You have no defense to soak up incoming fire. Your entire survivability henges on you staying the hell out of reach, or getting out of reach ASAP. your Chaos 5 trait helps a bit, and can be a life saver, but it isn’t going to stand up to much. If you don’t pack Null Field with you, it’s not uncommon to escape a bout with low HP and stacked conditions that will kill you gradually since you can’t cleanse.
If you happen to not react in time, a flurry of ranger skills, or a thief, can just wreck you instantly. Not that thieves can’t wreck anyone instantly…
So it’s important to be quick on your dodging/blinking.
But that’s how I ran it for the most part. I’ve recently changed to put a bit more into Illusions and a bit less into Duelist so I can take advantage of Shattering more.
https://forum-en.gw2archive.eu/forum/professions/mesmer/How-to-be-a-monster-mesmer-in-WvWvW-The-guild-and-the-zerg