New to fractals, would like help :)
This has a pretty good list of when to reflect anything. One thing that isn’t in those notes and that Anet will probably change soon is Mimic. Catching Mossman’s agony axes, or the crazy cat lightning balls will allow you to store an agony attack. Mossman’s axes are better as they bounce. Bosses that inflict agony attacks are immune to agony damage but the rest are subject to instant KO. You need to actually survive it and not get downed.
I usually tell my party to tag the enemy first as you can prevent them from getting champ bags. Favorites are the ice elemental mid point boss and the harpy mid point boss room. Dredge midpoint if you are good at staying alive. You can store the mimiced attack even when you don’t have echo/mimic on your bar. You will see a ball of energy on your left hand. If no good opportunity comes up then just look pretty as you stroll through to the jade maw knowing you never got downed once.
For the build, I suggest you to use a DPS build based on reflect: http://tinyurl.com/mesmer-dps-build
This is the DPS build you want to use. It allows you to have decent personnal DPS without having to rely too much on your phantasm since they die so fast. You can use GS when you have to range (like the imbued shaman and archdiviner for example), but melee DPS is the best DPS in the game.
You can also change the master trait in dueling and take Deceptive Evasion or Duelist Discipline or even Blurred Inscription instead of Phantasmal Fury if needed.
As for utility skills, you will almost always have Feedback and at least one mantra (for the dmg bonus per readied mantra, usually Mantra of Concentration or Mantra of Resolve). You can also take the healing Mantra or Ether Feast if you prefer. The last utility skill can either be Null Field if you need condition removal, Blink to skip trash mobs, Signet of Inspiration to double your allies boons, Portal when you need it or another mantra. You can also use Illusion of Life for the Ascallon fractal for example at the last area. The elite will almost always be TimeWarp