such a great Idea and finally the room is good for something....
If you are 90 the best place I found was in the Scenario "Crypt of Forgotten Kings" yeah you need to queue for that and do all the trash and stuff, but this only takes 5min and if you convince your group to let the sha pools live they spawn shas for forever and ever. I got 375 in 15min so 1,5k per hour.
Link for the Mobs you farm
I also made a video for this but I won't post it because I always do that so, not this time.
*wow there are many posts about charms farming* - edited because of that.