This quest can be deceptively difficult. You only have to harvest crystals from the big crystal formations found throughout the Draeni village called The Fallow Sanctuary. It's the area in the north-northeast of the zone. I found that the Draeni character models blend VERY well with the surrounding swamp, so what looks like an easy one-on-one kill can become two-on-one or even three-on-one. It doesn't help that the mobs are level 37-38.

If you have the patience and want to play it extremely safe, you will usually find one or two crystal formations with only one nearby mob. Just loot those and wait on a respawn.

Due to the fact that the Draeni blend in, and they tend to run when their health is low, you can end up with some very nasty fights, so it's not a bad idea to bring one or two friends for backup.

You can accomplish much more than this quest in this area, though. If you are allied with the Gelkis centaur in Desolace, one of their later quests sends you to retrieve a gem from Ongeku, who is found in the northwestern part of the village. Near him you can find a caged human that starts an escort quest. Finally there is a rare spawn chieftan that tends to spawn near Ongeku.