The Phoenix tribe built a sacred tomb for one their greatest leaders. For centuries, they have defended the land surrounding and the tomb itself.
A defense system was built so that only the team that has the tomb under their control may cap the flags. Of course, the enemies may still enter through either of the two doors, but the many turrets will cut them down in seconds.
The control switch floats above the tomb on a platform, with two AA turrets on each side.
The Forcefields defending the flags insde can be passed through if that player's team controls the tomb. They must take the flag all the way to the other side of the base quickly.
If the other team switches the control to their side while enemies are in the tomb, the turrets located throughout will kill them quickly, so you must get in there, get the flag and get to the enemy flag before this happens.
A few spots inside the tomb are safe from turrets, and you can hide there until possession is regained.