I'd go for Stupor if I had to chose one. Chances are if I'm using Stupor I'll already have some discard in the deck anyway. In a discard deck this could lead to overkill on discarding, but if that's the case then I've managed to empty their hand anyway. As for Stupor vs Unmask: I pick Stupor again, the 1 more mana you pay for Unmask is for its pitch ability at the cost of not being able to remove lands from their hands. I'd rather get to chose land as well, I like playing landkill in any place I can Doomsday Specter: A Coercion with hands and feet. Can't lose with this guy, I use his bounce "drawback" on Raveous Rats to get another card. Too bad discarding creatures don't deal a great amount of damage, and you often have to ping them to death, but it works well enough.