It has only happened twice, but it is extremely frustrating and could become a bit of an issue if it remains a viable tactic in 4v4. While playing somehow all four enemy combatants made their way into my team's spawn and proceeded to kill us before we could fight back. I don't think being able to enter into an enemy's spawn should be impossible, but I do think there should be some sort of debuff for hanging out in an enemy camp, or perhaps immunity from damage for the spawn natives while they're there.