GearOne thing to note is that Traits and Utilities make a shatter build much more so than gear, so you have a lot of freedom when choosing your Weapons/Sigils/Runes. The only weapon I would strongly recommend is a sword main-hand in at least one of your weapon slots. I personally prefer Sword/Pistol and Sword/Focus, but there are other viable choices, staff, greatsword, dual wielding swords. When it comes to weapons on a shatter Mesmer, stick with what gives you the best results, because being a Shatter Mesmer is more about your Traits / Utilities. For Sigils on weapons, my main hand sword get Sigils of Superior Fire to beef up the damage with a solid 1000 AOE damage 30% of the time you crit, while off-hand weapons you have a lot more choices. Another popular choice and solid option is taking Sigils of Superior Energy to keep you dodge rolling (this is typically coupled with the Trait Deceptive Evasion). With amulets and jewels, go either Berserker's for more damage output or Knight's to be more tanky, although I prefer Berserker's in most situations. Last but not least, for Runes I go with Superior Rune's of the Eagle for even more Precision and Crit Damage.
Skills and TraitsFor skills you have a few solid choices, and remember, outside of combat you can switch out your skills to adapt to your opponents and snag the victory. Your heal skill should be Ether Feast. Utility skill choices should be Blink (or Portal, which can be handy sometimes), Mirror Image, and Decoy. For the ultimate, go Moa Morph.
Blink adds a solid amount of mobility, letting you get somewhere faster, run away better, or even help chasing down a wounded foe. Mirror images summons 2 clones, which is key to the Shatter Mesmer, and will be explained in the Play Style section. Decoy gives you stealth and summons a Clone, which is great for sneaking around, getting away, or disguising your ultimate being cast. Speaking of, your ultimate Moa Morph is an amazing spell which completely shuts down 1 opponent for 10 seconds. The only problem with Moa Morph is it can be blocked and dodged, which is why I prefer to cast it from stealth, so the enemy is not able to see the cast animation and dodge the spell.
Go 20 down Domination, taking Mental Torment and Shattered Concentration. Mental Torment gives you 20% more damage with Mind Wrack, and Shattered Concentration makes all your Shatter skills remove a boon on hit. Going 20 points down Domination also gives you +200 power, +20% Condition duration, you inflict 5 seconds of Vulnerability if you interrupt a foe, and any Daze also causes 3 seconds of Vulnerability.
Go 20 down Dueling, taking Blade training and Duelist Discipline (if you have a sword main-hand & pistol off-hand). Blade training gives you +50 precision with a Sword main hand or spear while reducing sword/spear cooldowns 20%, and Duelist Discipline increases your pistol abilities range and phantasmal duelist range while reducing pistol cooldowns 20%. One alternate option discussed briefly in the Gear section is to instead take Deceptive Evasion, which gives you a clone if you successfully dodge, which works great when paired with Sigils of Superior Energy. Going 20 points down Dueling also gives you +200 precision, +20% Critical Damage, you gain 1 second of vigor on critical hits, and Illusions inflict bleeding on critical hits.
Finally, go 30 down Illusions, taking Precise Wrack, Master of Misdirection, and Illusionary Persona. Precise Wrack gives you +10% critical chance with Mind Wrack, Master of Misdirection makes all confusion you inflict last 33% longer, and Illusionary Persona makes the shattering effect happen on yourself as well, effectively increasing your shatters by 1/4 and giving you a plethora cool options, as the explosion from your clones will also come from your own body. Going 30 points down Illusions also gives you +300 Condition Damage, reduces Shatter cooldowns by 30%, your Illusion summoning skills recharge 20% faster, all Shatter skills inflict confusion, and shattering illusions grant you Might.
Play StyleThere are certain Traits you must take to have an effective shatter build, and they are Mental Torment (10 down Domination), Precise Wrack (10 down Illusions), and Illusionary Persona (30 down Illusions). These 3 traits are what gives your shatter Mesmer a solid amount of burst damage when you execute your main combo.
Your full combo, if all your abilities are up, first off get close to your target and stun / daze / immobilize them (Pistol 4/Sword 4 are great at this) if you can, then summon 3 illusions by using Illusionary Leap (sword 3) and Mirror Images, hit them with Blurred Frenzy (sword 2) and while in frenzy activate Mind Wrack, which will shatter all 3 of your illusions, produce the same effect from you, and not interrupt your frenzy combo (which not only pumps out damage, it also distorts you for 2 seconds). This combo will probably crit about 3 of the 5 (4 shatter effects, 1 frenzy), which will likely proc your fire Sigil. The grand damage total of this combo depends on if you crit and how squishy your target is, but assuming 3 of 5 crit and the target is not a tank, you are looking at about 8,000 - 10,000 damage in a small AOE.
Outside of your combo, Shatter Mesmer's have 1 cool mechanic that really puts a whole new spin on the profession, and that is because of Illusionary Persona. Remember, you can produce the shatter effects from yourself, without any illusions in-play, and doing so does not interrupt a channeling ability. Is your opponent casting a big spell? Use the Diversion Shatter on yourself, boom, he is Dazed for 1 second. You trying to finish off a pesky Guardian / Warrior / Ranger and know they will CC you in mid animation? Use the Distortion Shatter on yourself, and bam, you are immune to the CC for a 1 second window, which if timed right, means the CC passes harmlessly through you and you get the finish. Illusionary Persona opens up a lot of windows of opportunity for you to control the flow of battle and dictate the fight, making Shatter Mesmer's all the more fun and powerful.
At the end of the day, either way you slice it, no plan is bullet proof and everything has a counter. People can dodge roll your Shatters, AOE your illusions before they can do anything, and sometimes even focus fire you down so fast you die before you can react. It comes down to player skill much more than having an 'unbeatable' build, and the Shatter Mesmer build, while good, is far from unbeatable.
Tips, not Mesmer DependantI mentioned these 3 tips in my previous Warrior Build/Guide, so here they are again. If you want to be a good player who wins a lot, no matter what you play, you need to suck it up and really want to learn the game. Play every Profession, understand their strengths, weaknesses, and capabilities, read up on builds online, try out a lot of builds. If you lose to a particular Profession or build a lot, don't complain and gripe, figure it out so you can crush it. Play to learn, not to win.
Another tip is read the enemies' buff/debuff bar, and know what all the icons mean. This is something that really separates good players from great players, as reading the bar and knowing all the icons lets you react perfectly to your opponents choices, and execute the counter. A good example is if a Guardian activates stability, guess what, don't stun him, wait a few seconds then stun them. It sounds simple, but reading the enemy bar while fighting can be tricky at first, so keep on it and you will get it down.
The final brief tip, is do not be afraid to 1v1. This is crucial for skill development in this game, as you have to be brave and get beat down a few times to learn what to do against certain builds. So get out there and take em on.