Werebeast. The Werebear is immune to the special powers of champions base level 6 or less and their attached cards.
Copyrights:
TSR
Wizards of the Coast
Any card that has the word "immune" on it is worth considering for your deck. The Werebear ranks right up there with the best of the immune champions. There are plenty of annoying low level champions like Bilago Lumen (17/PO) or Sparkle, Crystal Dragon (35/DR) that make this a very worthwhile card to play with.
Not only is the Werebear immune to champions, but he is also immune to any and all cards attached to them including spells, unarmed combat cards, allies, psionic powers, blood abilities, magic items, etc! The Wearbear does not protect against events played into battle, though, because they are not "attached" to the champion. Even an event such as Complete Surprise (25/NS) would still affect the Wearbear. This immunity is not just a battle immunity - it works in the pool also to protect against things like Lyr of the Mists (23/PO) and Agis (261/3rd).
As with nearly all cards, the Werebear must be in play for his immunity to activate. This means that the Werebear card is not immune if it is in the hand, discard pile, Abyss, Void or Limbo. Hettman Tsurin (257/4th) can still pluck the Werebear from an opponent's hand with his special power since cards are considered to have no special power until played.