One more bug/oversight:
You can block Frederick using circle of candles and then talk to him about bloodstone while standing outside of this circle. When the dialogue finishes, he will disappear instead of starting fight with you. I managed to let him stay and attack me only by staying inside this circle myself and then teleporting outside using pyramides (it was the only reasonable way to defeat him at level 9 for me).
Same effect happens with some other NPCs when they are blocked in circle of barrels/crates/candles and can't leave it. But there is number of NPCs who reacts as expected. For example you may block Kadraskaz and he won't disappear.
