When doing the "Repair The Tower Heart" quest, go to the last sanctuary in the 
wasteland after collecting the tower heart shards and returning to Faye. When 
you enter the room where the heart is lodged in a gnome hole, move the heart 
after positioning ten brown minions at the bottleneck near the netherworld 
portal, and five red minions behind them for precautionary measures. The gnomes 
coming out of the hole and trying to attack you will run into your minions. 
Collect all the crystals for easy money. You can also get the "Gnome Grinder" 
trophy.