Start at the bottom-most part and build as many resource collectors as possible. Then, capture the Shipright. Get Builders to build Wall Hubs where the Cave Trolls lair is found (kill it first) and build a wall. Then, build units and an upgrade structure. Get your units upgraded as much as possible. Put some by the wall to defend it, then send the rest to the Shipright. Build the number of transports needed. Put the units by the Shipright onto the transports. Send the transports to the enemy camp. Another way is to split your units up and surround the camp. Destroy all the structures except for the fortress. Finally, destroy the fortress.