GamersGate have individually slashed the prices of Magicka and almost all of its DLC, meaning that you can nab the base game for the default 'deal' price level of £2.40, or grab all nine bits of DLC thrown in for an extra £2.09 - including the Vietnam and Nippon expansions. Note that the collection doesn't include The Stars Are Left, which can be brought seperately for an extra £1.98 (also discounted). Just in case there aren't enough options for you, the four pack has been slashed down to £7.19, making a single copy worth £1.80.
In case you haven't heard of Magicka, it's an anarchic and irreverent magical action game that allows you to combine insane elemental spells into a countless selection of brutal, beamish, brilliant beams, balls and thunderous death rays. It's also probably the only parody game that manages to take the mickey out of standard RPG cliches without perpetrating them itself, and the multiplayer is still an absolute joy.