Is convection really that bad? I am only level 31 and don't really know how hard each dot ticks but I thought Crushing Darkness was bread and butter of Madness. Also the instant lightning strike. has extra damage to if you choose to use you instant cast on that.
http://www.torhead.com/skill-calc#201hZbc0MZcMfRsMkrfz.1 is what I was planning on using.
I was also kind of considering
http://www.torhead.com/skill-calc#201hMMZ0cZcMfRsMkrfz.1 for paracitism healing. I don't know how good it actually is though since the dots have to crit...