If you ask me, Magicka has enough "PVP" as it is in its default co-op mode. There's so much friendly fire going around that most people in a full party accidentally kill each other as often as the monsters. But no one asked me, which is a good thing, because then we'd have none of this hilarious new stuff to celebrate the game's new, free PVP add-on.
Besides three new modes dedicated to having wizards grief each other, the free add-on comes with the new "Reservoir Robes" costume. Those willing to cough up some pocket change can also purchase four new DLC packs: The "Party Robes" costume pack and the Watch Tower, Frozen Lake, and Final Frontier maps. That last map comes with extra gear to complete the whole "We're ripping off this Star Trek scene," shtick.
Oh, Magicka. How I cherish your silliness.