Shattering is an exclusive ability to mesmers. Shattering destroys all illusions and applies a secondary effect. There are four shattering skills, all of which are instant-cast and have different cooldowns. Shattering skills are more effective if you have more illusions active prior to shattering them. Mesmers start with two shattering skills and earn the other two at early levels. 
List of shattering skills
|Shatter||Mind Wrack||15||Destroy all your clones and phantasms, damaging nearby foes.|
|Cry of Frustration||30||Destroy all your clones and phantasms, confusing nearby foes.|
|Diversion||45||Destroy all your clones and phantasms, dazing their target.|
|Distortion||60||Destroy all your clones and phantasms, gaining Distortion for each one shattered.|
Traits that affect Shatter
- Rending Shatter - Illusion apply Vulnerability upon shred.
- Shattered Concentration removes boons when shattering.
- Restorative Illusions heals a small amount when you shred illusions.
- Shattered Conditions removes a condition from you when shattering.
- Vigorous Revelation grants vigor to nearby allies when you shred your illusions.
- Illusionary Retribution adds confusion when shattering.
- Illusionary Invigoration recharges all of your Shatters at 50% health.
- Illusionary Persona cause the shatter effect on yourself as well when shattering.
- Shattered Strength grants you might upon shredding an illusion.
- ^ Fortryllende illusjonist
- ^ GW2Guru Reddit AMA - All Questions + Answers
- ^ Gameplanet: ArenaNet's Jon Peters on Guild Wars 2