This is a really solid demo! I love the monster sprites (I think Greatfrog is my favorite...it has a powerful aura), and the battle UI is very clean.
I didn't understand Blight at first, but I went through the demo a second time with a party full of Mr. Sams and obliterated the roaches with Cold Touch/Sing Song. That's a really awesome mechanic.
The only gripe I have is the controls - having the ability to use something like arrow keys/Z/X instead of WASD/J/K would be nice.
I'd be more than happy to play this game again if you work on it in the future.