Defense Points: 1000
Enemy Spawn Point (Ground): Four
Enemy Spawn Point (Air): None
Target to protect: Two main cores, two sub-cores
The two main cores can be approached on both sides each. The Flooded Catacombs and Echoing Tunnel leads to the northern main core. Deeper Caverns and Ancient Sluice leads to the southern main core. You can quickly reach both cores by crossing the pipes in the middle of the map. (Be careful not to fall) Also, avoid falling on the narrow canals or you'll get swept by the water current and die.
The Flooded Catacombs path will pass through the northeast subcore while Deeper Caverns path will pass through southeast subcore. Both main cores can be approached on either sides so it's important to place defenses along the chokepoints, especially near the narrow stairs.
The only traps in the map are the pressure caps found along the path from Ancient Sluice. Barricading the path near the Deeper Cavern's entrance will allow you protect the path from Ancient Sluice, leading to the southern main core's eastern side.
One barricade is enough to stop the enemy flow from the Flooded Catacombs and protect the northeast subcore at the same time. Make sure to reinforce it with other ranged towers and traps and regularly repair and upgrade that barricade.
The winding path from the Echoing Tunnel is perfect for placing traps that will whittle down the enemies' HP with the support of long-ranged towers. Barricading the stairs and the narrow path will also stall enemy movement. Make sure to place boosts and other supporting traps to force enemies to group together and suffer AoE (area-of-effect) damage.