Do you have any expansions? I guess you do if you boosted a mesmer so i'm gonna assume you have acces to elites too, so here's some tips.
You really have to play the class a bit to understand what it does and how. That's true for all classes, but especially true for mesmer.
Your primary mechanic is creating and shattering clones. Depending on your build, you'll either use this constantly or ignore it entirely (weird, i know). Clones look exactly like you and other players can't differentiate them from you and they deal 1 damage, but can deal conditions, especially Mirage ambush skills (if you have the right trait). So if you primarily want to do conditions, you'd choose a build with clones and shatter them a lot. Phantasms look like ghosts and deal a lot of damage, but unlike clones, it's not wise to shatter them (although you can if you need to daze a boss to break its defiance bar etc.). They do more damage the longer they stay alive.
So there's a shatter build, and a phantasm build going on basically.
Shatters:
F1: Power shatter, scales with power, does damage and nothing elseF2: Condition shatter, scales with condition damage, applies confusion (which deals damage + extra damage when the enemy uses a skill)F3: Daze shatter, good fro breaking boss defiance barsF4: Panic button, use it when you're about to dieF5: Chronomancer only - Shatter clones and make a "copy" of your current cooldowns, health and some other stuff. then after a few seconds (depending on how many clones you shattered, you return to the exact place you used it with exact cooldwons and health you had prior to shattering. It's extremely tricky to use, but once you get the hang of it, you basically get free skill casts and can even revert to being alive after being downed.
Weapons:
Sword: Good power weapon, has distortion (evade) while dealing damage, and the off hand sword phantasm is the highest damage dealing phantasm mesmers have. Duals swords is great for core mesmer and chronomancer. Has a block.
Greatsword: Ranged power weapon, doesn't apply conditions, kinda lacking all around, but pretty good for farming trains and when you need to keep your distance, because the farther away you are from your target, the more damage you do. GS phantasms hit an area, but are slow.
Staff: Power weapon (although you'd mistakenly believe it's a condi weapon because it applies conditions - that's not why you use it). Great evade skill, not much else. Staff phantasm deals more damage the more conditions the target has so it's great for world bosses that have players apply thousands of conditions on them, but it scales with power, not condition damage. Chaos storm can provide a combo field (axe 2 will apply more confusion if executed inside a chaos storm) but is on a long cooldown. Staff is kinda all over the place and people don't use it generally, but it's fun to play with when you're not required to do damage of for world bosses where no one cares what weapon you're using.
Axe: Condition weapon. Can apply around 30 stacks of confusion with a proper combo and has a lot of mobility, Mirage only. Axe 2 generate clones, fastest clone generation weapon mesmers have.
Scepter: Condition weapon, autoattack slowly generates clones, has a block, and scepter 3 skill applies confusion. Unremarkable otherwise, but good to combo with the axe when you want to apply more confusion than you'll ever need on a target.
Focus: Utility weapon. Phantasm it creates is weak but it reflects projectiles and looks cool. Not very useful a lot of the time, but sometimes it can be. Focus 4 gives you a field you pass through to get haste, and the second time you activate it pulls all enemies to it's center. Pretty handy for focusing minibosses (like golems in chaos fractal), so that your party can decimate them faster and all in one place.
Torch: Good off hand for power builds because the torch phantasm gives you and your party ferocity (critical). It also burns stuff and focus 4 has stealth which is not that useful in PvE, but it's good for WvW and PvP. In PvE, stealth is ok for legging it when your other survival skills are on cooldown or for initiating fights since it burns enemies when it ends.
Pistol: Power/Condition weapon, depends on your build, but if you use sinister or viper's (power, precision, ferocity +- expertise) gear, it's critical hits (along with a proper dueling trait), will cause bleeding on targets, so it will utilize most out of that 3 stats, it scales with power, needs critical chance to start bleeds on targets and that bleed is then affected by condition damage and expertise. Pistol 5 is a good breakbar skill and good for dazing trash mobs because it jumps from one to another.
Shield: Chronomancer only, has more utility than i can count especially due to Shield 4 giving you 2 blocking chances, and it summons a phantasm for each block that gives Alacrity or quickness to you and your party (skills cooldown faster - cast skills faster). Shield 5 gives stuns and quickness i think. It's really good if you're a chronomancer and you should always have it in any chronomancer build.
Aquatic weapons: Both are useless and not worth talking about. Spear is kinda power weapon, trident is kinda like staff but meh...
Specializations:
Domination: Good for interrupts, applying debuffs to enemies like weakness and vulnerability.
Dueling: Great for power builds and phantasms since you'll be keeping your phantasms alive most of the time and won't shatter then. Then traits like Fencer's Finesse combined with a sword/sword combo can really hurt the longer your sword phantasms are alive.
Chaos: Focused on condition damage and shattering clones, gives you boons for shattering, condi damage the more toughness you have etc. Tanky shatter specialization.
Inspiration: Help your party with magic. Don't use this solo, it's not really for solo play, but it has a trick. Restorative mantras will heal you and allies when you finish preparing a mantra. Then just put Mantra of pain on auto attack and GG you're invulnerable because that mantra will damage enemies, deplete after 2 casts and you'll automatically prepare it again which will heal you. I don't know if this still works, but it worked great for core mesmer builds.
Illusions: Kind of a must have for either shatter or phantasm build, but which traits you take depends on what you want to do. If you want to keep phantasms then you'll take Phantasmal Force which will increase their damage the longer they're alive. If you want to shatter you'll instead take Master of Fragmentation which improves your shatter skills.
Mirage: Confusion, shatter, confusion, shatter, evade, evade, etc... You get ambush skills different for each weapon, but the best ones are from axe and scepter for condi and sword for power. You get mirage cloak which means you can evade while standing still or reviving someone (it doesn't break your actions so wether you're attacking or reviving or whatever, it will evade unlike a regular dodge that will interrupt whatever you're doing. Generates tons of clones with Self Deception trait and makes all your clones use an ambush skill if you have Infinite Horizon trait selected. Best for condi builds, but great for power too (albeit a bit specific, power mirages are kinda more PvP oriented).
Chronomancer: Can use wells, has Alacrity, and is generally a support role. Use this if you want to raid, but the rotation for the chronomancer has ungodly amount of complex steps so beware. Complex to learn, focused on party support with low personal DPS, but great breakbar skills.
I won't go into detail about utility skills since this is already too long but just a few notable ones:
Signet of Humilty: Completely depletes a boss' breakbar in most cases. Or turn someone into a moa, whatever...Signet of Ether: Heal and reset phantasms so you can cast a second one right away. Use this in phantasm builds.Other signets give you condi damage and duration or boons.
Portal: If you played the game, you know what this does. People will love you then discard you like trash when they're done with you. You get used to it. Sometimes you'll get money for portaling people to difficult jumping puzzles, just don't ask for money, it's not cool. If they donate, great, if not, it's ok. Use mimic before you cast the exit portal to make it refresh faster.
Blink: Your best friend in WvW.
Jaunt: When you have Self Deception trait, Jaunt (and any deception skill) generates a clone as long as you have at least one active. You can also use it to get out of AOE and stuff.
Feedback: Reflects projectiles. Extremely needed in some situations.
Mantra of Pain: With Inspiration specialization, can heal you as you deal damage (if that trick still works). Since it will be on auto attack, after a while you'll start to notice the brain damaging sound the mantra makes when prepared, and if you didn't turn off player chatter, you'll want to strangle your character after just a few hours of using this because they'll constantly spew the same lines over and over. That's the tradeoff of being constantly healed i guess lol.
Gear:
Core Mesmer: Berserker (power, precision, ferocity)Chronomancer: Commander's and Minstrel's gear because of boon duration, or berserker's if you're on a budget.Mirage: Viper's for Phantasm mirage or Trailblazer's for confusion shatterer mirage, both have expertise (condition duration). Trailblazer's will bankrupt you, but you can use dire instead.
Here's the build i use (with sample gear, you can use dire instead with nightmare runes, the gear i put there is expensive):
This build will make you just make clone after clone, and shatter them for tons of confusion. Plus, you're tanky.If you want, i can make a few core mesmer builds in this tool, if you need help.
