Arrowhead has hinted around that after Magicka: Vietnam, they'll finally be bringing player vs. player combat to the series.
A pair of messages on the game's official Twitter page read, "How about an achievement for defeating a developer/paradox? A good way to vent your frustration - yes? Wait, we need PvP for that ... we better build it right after#MagickaVietnam then."
Stay tuned for more info.