Hey guys, I found this nice little bug with the crystals Corborus summons on Heroic mode.
Only works for the first lot of crystals unless you jump back up there.
Picture #1
There is a part where you can walk slowly and then jump to get on top of the rock. Get everyone except the tank.
Have the tank pull the boss back towards the rest of the group.
The shards will be spawned ontop of the rock and as they spawn, everyone jumps off.
The result = This.
Picture #2
The crystals cannot be attacks and cannot get off of the rock. If you have hunters in the group, the pets stay ontop of the rock and cannot get off, so put then on aggressive and they will kill the crystals and die themselves (unless you heal them or revive them after). This process can be repeated if you are fast at getting onto the rock.
Hope you find this helpful. Gets rid of the crystals for lower geared groups.