So I was fighting the barrier demon last night. I'm on my third try and I get him down to 500 life points, and I run out of cards. I was so upset. I stacked my deck with a ton of converter, fire shields and helephants and kept my treasure cards really light that I actually ran out of cards. AAARRRGGHH. Going back tonight and this time he is MINE. Oh and for all those that don't understand why he keeps asking for the blood again if you go back a second or third time - just go over to the fire brazier which will reset the demon so that he fights you. You do not have to go back to the witches coven.