Good idea.
You could have the same with Predators vs Aliens, Predators must enter the nest and capture the queen, moving from chamber to chamber, aliens must defend the nest at all costs.
The reverse would see the predators fighting there way out of the nest, they must protect the queens shackles, aliens can get close and damage the shackles with melee attacks, once they are broken its game over.
Pretty simple to implement as well, but it probably wont be added due to the laziness of the devs.