This is an odd mission. There are four enemy bases and you can only reach one of them on the ground. You've got to have some air defense as a consequence because the humans, orcs and undead will all send their respective air units at you. You begin in sort of a rough spot. The gold mine to your north doesn't have much in it. Still, walk your treants north and root them there however you like. Attacks won't be coming from the south however as there are no entrances to that area except from the air. Your first goal should be to create an attack force with the little resources you have available. Plenty of Archers should suffice and maybe a couple dryads. Build four more wisps than you currently have and set them to gathering wood. They'll be fine in the southern part of your base and you can leave them there throughout the mission. Do some scouting with Tyrande's owl and you'll see some trolls to the east of your base. Get a few archers trained and add them to your forces then kill them.

It will not be long before a group of wyverns attacks your base from the north. Kill them but don't worry about the second group as they're likely the six that come to attack the gargoyles. Let them. When your forces are sufficient head east and attack the trolls. Their leader drops an ironwood branch (+1 str) and Furion can use the experience from this battle. Don't leave your base undefended as you now head off in search of a better location to get gold. Which is not found to the east, exactly. This mine has 2000 in it but you're not in a position to complain.

When your forces arrive you'll encounter the furbolgs from the first mission. They've been corrupted and are set on attacking you. Kill them and you'll receive an optional quest. You may have taken some losses from them though as they're rather strong. Take your tree of life over to the gold mine and entangle it. I left the rest of my base as it was, instead keeping my hero at the gold mine for a minute or two to protect it while I built two additional wisps and made them into ancient protectors. These guys are gonna follow the gold mine entangler around. Rebuild your forces but this time build a couple more huntresses to go with you. Perhaps even ugprade to moon armor! This will help your units last a little longer in a cash strapped situation. Now we'll find another gold mine.

The mine I recommend you nab is under the control of the humans in the light blue base to the east. It's behind a gate but when your forces approach that gate will open. The base is poorly defended and the gold mine has another 2000 gold in it (roughly). Move your tree of ages and its protectors to this new location and gather the resources. Purchase a unit upgrade or two and replenish your forces. Before you tackle the optional quest head to the northeast of the orcish base. You'll find a fountain of health there and a lot of trolls. Kill off the troll and you'll find a ring of protection +2. Destroy the crates and such behind him and you can find a tome of strength. We're going to do the optional quest now:

Optional Quest: Crazed Furbolgs
You can use the owl scout to follow the path you'll have to take to get to the warlord. The path is directly north of the gold mine you had just before the human base. Notice how it curves around with many small groups of furbolgs and ends in the northwest, finally, with the chieftain and his guards. This is not going to be a very easy quest but you can do it! And, at least you'll get some gold for killing the furbolgs to enable to enable you to reinforce your army. I took Tyrande, Furion, three dryads, three huntresses and four archers. Take your group out to the north and begin the battles. The first one isn't so difficult and will likely cause only minor damage to your units. The second, with the shaman may prompt you to send your forces back to the fountain of health to heal. Don't worry about it! There's no timer here. Heal up or whatever you have to do and continue on. The final battle with the warlord is definitely the toughest though through the entire thing I only lost one unit. When you've killed the warlord you get claws of attack +6. Now it's time to do another quest.

Optional Quest: Cursed Glade
Break down the gate in the southwest corner of the base you captured from the humans. This long path is the road to the barrow dens and this quest. Use the owl scout to locate targets of opportunity. When you first enter the area you're greeted by several units who you should keep in reserve as reinforcements. Begin by heading south, keep an owl scout in front of you at all times to deal with ghosts as they can posess your units. But not your heroes. Use the heroes and only the heroes to kill ghosts. Your heroes should be strong enough to stand on their own against a few level 3 ghosts by now, heh. Make your way slowly south. We'll reveal this entire area and kill everything in it! Nah. You don't need to go that far, you can just make your way to the death revenant. He's in the southeast corner of the map. It's a long road to get to him though as you will likely be ambushed by many undead rising from the ground. I think there's an endless supply here so I suppose if you ran out of gold you could do some hardcore creature slaying wth your heroes. At any rate, there's no need to fight all these battles. Fortunately there's not an endless supply of ghosts so just keep making forward progress with your units. The death revenant is protected by several powerful units including wraiths and dire wolves. Kill them off then focus your fire on the revenant. The entire forest will be cleansed of evil allowing your units free passage. It certainly makes getting reinforcements for the next part easier! Also north of here you can find a gold mine which has 5000 gold in it. This may come in handy if you're going broke.

Finally we'll push toward the barrow den. You'll want to bring a couple of ballistas with you this time. Your owl scout will reveal a large corrupted night elf base in your way. You will have to destroy every last thing in this base to complete the mission. Fortunately the Satyrs and skeletons aren't very powerful .But they come in huge numbers. As such a force tending toward more huntresses is preferable as they can deal damage to multiple units. The most annoying thing are the corrupted ancient protectors. Ballistas can destroy them without taking a scratch though. Just protect them from the attacking enemies. When you've wiped the area clean, take Furion to the barrow dens and you're done.