Mission 50

This level has a random set of portals that tend to link the top of the level with the bottom of the level. You can take these portals to get to the top quickly so you can destroy the bombers before they make life too difficult. You should try to destroy everything before the gate. This includes the barriers too, since the Elite Overlord will destroy them, on contact, and use their resources to create trap drones.

The death ball swarms that the Elite Overlord summons are more dangerous on this level since the portals are situated in a way that makes loops more likely.