Have 2 teams, one with monsters & one as hunters, have the monster (Goliath?) with the ability to drop a limited number of eggs at one time (5), allow the monster to set up a base - maybe with a hive (basically the monsters version of the power relay), once the hive is set the monster can lay down some eggs, the eggs in turn hatch minions (as normal) but allow the minions to be controlled by actual players with similar HP as (minions) now & a select number of points for abilities, even have a few defensive structures that cause splash damage when a hunter is near - spitting ooze for example (think of an egg that has spitting ooze out the top) & allow the main monster to place these at a point of his choosing.
The hunters have their power relay that is also mobile at the start, the first hunter (engineer type) can place the power relay at a position of his choice & have a select number of turrets he can place also, as normal (like in defend) they have to defend the structures/power relay against the player controlled minions.
The first team to destroy the opposing objective wins, the monsters in other words have to destroy the power relay & the hunters have to destroy the monsters hive. An alternative way to win would be to kill all hunters or kill all the monsters & eggs.
I feel that something like this would add more of an end game to Evolve & it would be more enjoyable. Most of the mechanics are already in the game, so it shouldn’t be to hard to create.