I'm not a Mesmer in GW2 so I can't tell you about them...but Lunitari can SHOW you how awesome they are. On the left side it LOOKS like there's two clones...but then I pan out and there are THREE.
For background, this was the closing event of the June BWE. We had to kill players who were corrupted by a dragon and then defeat the dragon's champions.
This video can be popped out and viewed in 720p if your hardware supports it! Enjoy!