Managed to get Alarak to level 5 playing with a friend in QM. Though quick match games are usually a crapshoot, I settled on a lightning focused build which I felt pretty good about. Mana cost reduction, +range, extra healing, cooldown quest, sadism, both ulti's by level 20. It's probably actually a bit better in QM because there's often no supports on either team, so you can just zap people from range on CD and eventually they need to do something about it or leave to go heal.
A big thing that helped me when playing him is when I learned about the Alt + W thing (no mouse click) which automatically casts the Force Push on you and shoves you forward whichever way you are facing. HUGELY helpful for getting out of bad spots quickly instead of trying to get yourself in it with a manual cast.
He's fun and I was considering picking him up, but I should still probably grab the rest of the 2k/4k heroes I'm missing to try and round myself out for the Draft modes.