The Blue Hive can be found in the Moist Hollows outside Heavens Peak. When you teleport to the main waygate outside the city, you need to go down into the refugee camp and then follow the path down towards the water. On the other side of the swampy area youll see the blues hopping around the entrance to a cave blocked by a field of poison plants. Sweep your minions across the log bridge while you cross the shallow water and use your greens to access the Moist Hollows. The blues are very weak and youll have to fight a number of enemies throughout the cave, so youll want to make sure that you have a number of browns to do the hard work.

The biggest obstacle that youll face is a giant water serpent that prevents you from leaving. If you use your greens or browns and careful timing, you can kill the serpent without losing a single minion. Sweep six or seven minions back and forth in front of the serpent until it strikes. After it strikes, it will hold its head over the platform for several seconds. Immediately, sweep the minions onto the head and wait exactly five seconds before calling them back. Theyll jump off its head and back onto the platform just as it raises its head back into the air. Repeat this cycle until it dies and you shouldnt have lost any minions or taken any damage. Continue onto the teleport stone. The achievement will unlock as soon as the Hive has been teleported back your Tower.