If you pop Rank 1 Hellfire as a Warlock while any breakable CC is being casted on you or before it's casted on you, the small amount of damage you take from it will break the CC. This did NOT work before patch 2.3 so I'm calling this an exploit rather then it being "common knowledge."
If you feel a blind coming (after you trinket a fear or something) just pop Rank 1 Hellfire and BAM! Blind will last a total of 1 second
Between Devour Magic with your Fel Hunter and this new exploit, you shouldn't ever be afflicted by sheep again! Sometimes the dmg will break fear but it's rare ;o
All credit goes to Sorrow of Twisting Nether EU