Gnoll is a bit OP in the current build, and sorry to say, but he's getting a slight nerf. The shields he spawns will now be "Buckler Shields" which can only block 1 hit and if they're dropped they are removed from the game instead of being left on the map. I think he'll still be a very strong choice though.
I agree with the uselessness of late-game money right now. We'll eventually be adding minion upgrades and relics to the game, which will give you something more useful to spend your money on after you've got a perfectly balanced minion deck.
Thanks for playing and for the feedback!