Hello, this is my guide for lovely Charns.
First u go to Valley Of the Four Winds. Then of to "Pool of purity", slay turtles with 36k Hp.
They are quite alot stacked up at once and they spawn fast so its pretty damn good.
http://www.wowhead.com/quest=29600/snap-judgment <--- Same Spot where the turtles are located at, if u wanna have a image of it.
Around ~~~25-30 Charms a minute.
Another alternetive if much people at that spot.
Dread Wastes, killing Wasps with 16-31k Hp, they are stacked in bunches near the tree's really good spot aswell.
Waste Scavengers are found west of Forgotten mire if u waiting for respawn go kill them meanwhile.