16: Aker's Gate

Campaign

Waves: 9

Starting Energy: 1100

Lives: 20

There are two checkpoints you need to defend and fortunately there's a bottleneck where you can defend your position. Be careful of the teleporter behind the bottleneck since enemies in the later waves will use them to sneak behind your position. You can place a high powered tower to help defend that position. As usual, place rocket and laser towers near your position. Try to get a specialized tower up as soon as you can to help you defend the bottleneck more effectively.

Upgraded enemy types will be present here so unless you have upgraded your towers well, expect that you'll have a tough time damaging them. In the sixth wave, wasps will start flying towards your base. In the eighth wave, you'll have two groups of Hulks walking towards your base. They'll be pretty hard to kill even with fully upgraded towers so be careful not to let your towers focus on them only. They're tanking for their smaller, faster allies after all.

Veteran

Waves: 6

Starting Energy: 1150

Lives: 1

You can only build MG and laser towers in this mission. It's hard to scatter your towers early in the game since the normal enemies are tougher to kill by LV1 towers. Concentrate your defenses on the bottleneck and call in reinforcements as necessary. Be careful not to leave the teleporter exit in the rear unguarded since the enemies will use it halfway through the waves. A ton of Wasps will both use the main path and teleporter so make sure to use your Tesla Tower to once they appear out of the teleporter before they gon on seperate ways and slip past your defenses. The Quad Beam specialization for the laser tower is very potent against them but you need to have one installed near the teleporter exit behind the bottleneck.

Clear up some rubble and place more defenses. If you can transform at least one of your MG towers to a Railgun emplacement, it will help a lot in sniping targets at a great distance. Just don't hesitate to use airstrikes and reinforcements as necessary.

Spec Ops

Waves: 1

Starting Energy: 1200

Lives: 1

At the start of the wave, enemies will use the teleporter so focus your defenses around the teleporter entrances. One good way of dealing with this situation is to have a Quad Beam tower built near the teleporter entrance. This way, the enemies that will appear via the teleporter will be severely damaged. You can also place a rocket tower right outside the teleporter exit on your end to deal splash damage to the enemies as they appear. Build at least one infantry tower near the teleporter exit to help hold off the enemy forces. You have at least upgraded your infantry tower to LV3 to be able to hold off the opponents much longer.

After surviving the initial onslaught of mites, dry grunts, vampires, and sand slingers, you have to deal with multiple wasps. It will be tough to stop them all so make sure to have your tesla tower ready. It's almost impossible to stop the enemy advance by relying only on your towers and without using your abilities so attempt this mission if you're willing to use several reinforcements and airstrikes. Doing so will allow you to reap energy almost instantaneously and allow you to quickly build or upgrade your towers. Well-placed airstrikes (like when the enemies are grouped together on their way to the teleporter) will allow you to take out multiple enemies and gain a lot of energy all in one instant. Make sure to scatter MG towers around the teleporter exit as well and upgrade them to at least LV2 to help cope with the Wasps that may slip past your blockade.