-In order to do this you must have fought Dazzler Beetles (located in the blue minion cave), Puff Beetles (Evernight), Magma Beetles (outside of Heavens Peak) and Battler Beetles. After fighting at least one of each, they will be available at your dungeon. Go to your dungeon and choose to fight one of the four. The easiest way to take out the horde of beetles is to pull only a few from the swarm and take your time killing them individually. Green minions work well sincet they are experts at overwhelming and killing your enemies. Set a marker for them to wait at and they will eventually turn invisible. Pull a few beetles and make them follow you to the marker, where your minions will then jump on them and eventually kill them. Battler Beetles are good for getting Brown souls. Puff Beetles are good for getting Green souls. Magma Beetles give red souls and Dazzler beetles give blue souls. You should get at least 75 souls each time you completely kill all of the beetles that are in the dungeon.
-For fast green minion soul gathering, when you find the green minion hive you will see five green minions jump into the spawning pit for you to take control of. Do not do that. Instead, go to the tower using the gate beside the tree spawn pits to your right, then return to the green minion hive. Five more green minions will jump into the spawn pit and you will still have the ones from before. You can repeat this as many times as desired, but after you take the hive it will no longer work.