Have not seen this here before but iam not sure if its not too good for normal share. Well the point is MfD with mortal enemy rune gives you 3 hatred per each hit you do to marked enemy and since nether tentacles can hit fat enemies more than once ( they can hit stacionar bosses even 3x ) they return 6 - 9 hatred so the skill coast nearly no hatred at all.
I managed to get belial inferno phase 3 down only with nether tentacles.
best used if you have some tank or tyrael who can make enemy stuck.
+rep if you like it :P
PS: dont tell me its just clever use of mechanics since i realy dont thinkblizzard intented to make nether tentacle coast no nearly no hatred at all for any bossfight