User blog comment:Lukamarcic/3 Team map idea (lol)/@comment-132.205.7.99-20130320183733/@comment-3974211-20130321163346

The core of Easily solved by making it so that the objective isn't to "kill" the other team, but rather, capture them.

As proposed above - make the Nexuses "capture points". As such, even if two teams work together to kill the members of the third team - you cannot both capture their nexus. The two teams who worked together immediately have to fight with each other, and the longer they take - the more likely the third team is to respawn and clean-up the low healthers squabbling over their nexus.