discord, dissension (noun)
disagreement among those expected to cooperate
disagreement, dissension, dissonance (noun)
a conflict of people's opinions or actions or characters
An act of expressing dissent, especially spoken.
Strong disagreement; a contention or quarrel; discord.
Dissension is the 60th Magic: The Gathering set, 38th expert level set, and the third and final set in the Ravnica Block, released on May 5, 2006.