Follow the path down the hill. Ignore the path to the left. You open that path from the other side. So go down the right path.
When you reach area with a tree in the center, dead elves will talk to you.
They ask you to kill some unicorns. Follow the path to the left. The first unicorn is here.
Have your minions play with the horsy. Go to the left. You can cross the stream, but your minions can not. They can cross the green vine.
Make a guard marker near the green vine. Cross the stream. Once on the other side call your minions back.
Kill the second unicorn with your minions.
On the left side is a wheel. Turn the wheel to make a bridge.
Have the minions break the fence.
Have the minions grab the tower object. It is the Anger spell. The minions will take it to the teleporter.
Go back to the dead elves. They will move out of the way. Have the minions break the barricade.
Moving up the hill some rat like creatures will pop out of the ground. Have the minions kill them.
You will come across another dead elf. This elf will give you the quest to kill Oberon.
To the right of the elf is a barricade. Have the minions break it down.
Past the barricade is an Oberon node.
Have the minions do what they know best. Have them kill the node.
This will weaken the shield protecting Oberon. It also opens a new path for the Overlord. Go back to Oberon. Turn to the right and the root that was here is gone. Follow the path to the right.
As you follow the path, The Overlord will run across green minions. Now all you need to do is locate their hive.
Follow the path to the left. The green gas will kill your minions. As the path winds around the swampish area, you will see the minions outside a cave.
That is where the green hive is. Keep following the path. You will come across some weird things praying at an altar.
Do what Gnarl says. Hold LT to target the pod. Send a minion to grab it. Then move the minion in to the creatures and let go of LT.
Now the creatures are dead. Move the minions to where the creatures were and place a guard marker.
Now go to the right and down in to the water. Just go straight through the water to the land.
Call your minions to you. Get closer to those creatures. There is a pod to the right of the creatures. Or just attack them.
To the left of where the creatures were is a barricade. Have your minions tear it down.
Sweep the minions over the vine to the right and make a guard marker there.
To your left is some water. Cross the water to the land. When you get to the land some rat creatures pop out.
Call your minions back and have them kill the creatures.
There is also a summoning pit for red and brown minions. Replenish your army if you are low. Go to where the minions had been guard marked. On the left will be some rat creatures and some pods. Send a minion to grab the pod and drop it near the rat creatures.
To the right of the rat creatures is another pod. Send a minion to grab it.
Then sweep that minion in to the weird creatures and drop it.
Follow the path to where the creatures were. To the right is a barricade. Have your minions tear it down.
Past the barricade are more of the horned creatures and a pod to the left. Kill the horned creatures.
Just a little bit past them is a barricade. Tear it down with your minions.
You have made it to the cave. But before you enter, go to the right. There is a tower object and a bridge there. First have the minions make the bridge.
Have your minions grab the tower object and carry it to the teleporter. It will increase your mana.
Go in to the cave after the object is returned to the tower.