The buffs to both the total radius and explosion radius have made it far more consistent in dealing its damage, especially on just one or two targets, but its done very little to improve it when you've got an ally to help set you up for it. As nice as the slow is, unless you have an Agh's, its no more potent than Sand King's slow on his ult. Later on in the game it will do very little to prevent you from being killed almost instantly the second someone like PA or Void reaches you.
Personally, I'd like it to be changed to a channeled targeted spell like Warlocks Upheaval, with the damage lowered to far more sane levels. That would at least make it usable with some degree of safety, and without requiring Enigma, but would still be suitably risky that the other team could take advantage of it being used poorly. Perhaps even make it a shorter channel centered on CM, but have a gradually stacking slow and make it deal a huge explosion of damage based on how long it was channeled for would work too. It makes it risky for CM to use, easy for the other team to stop, but rewarding enough when used well. There a a lot of ways the effect could be kept similar with a rework of the skill, but for whatever reason Icefrog seems to want to make it work in its current form, its been getting an almost constant stream of buffs for a very long time now. I wont give up hope on it being changed entirely, but its not looking very likely at this point.