What does it mean to 'cripple' someone? Wulfsbane and headstrong both have abilities that inflict cripple onto an opponent and they're considered some of the best cards in game? I thought 'cripple' means to keep people from gaining positive abilities? but how does that make them strong? I have both cards and I don't know if I should invest the time into leveling them up since i dont really know what 'cripple' does.