I have tried to build a discard deck a few times. It isn't a bad mechanic. It is a REALLY bad mechanic. The only thought I have every turn is. Why am I not playing Zoo?
Card draw is definitely not the thing that will make discard a thing. It is Warlock. Here have a really risky way to draw cards. Hero powers. Thanks dood, I'm good, I'll pass on that.
I saw someone thought that maybe a combo warlock that draws through its whole deck in record time, and that seemed cool...sadly it discards the key combo cards that is collects as it does so...rip miracle Warlock.