Tried to see a similar topic but didn't.
Firstly, great game. Just about to head to Talushorn but already enjoying it as much as the first game.
So I was having trouble getting the diamonds at that necromancy site and surviving the attack of ghouls so i set a portal point outside the trap. I found that not only could i grab stuff out of a chest while being incapacitated by an enemy spell, but once I used the portal to get away from the enemies/chest I could still take things out of it if the box was still open.
I've used this a few times since if I need to get something without fighting heaps of stuff.