Was still tough for me because I had no healing items and less then half of my health but I ended up getting him... Didn't know you can meditate to recover that stuff either until later.
You can't meditate during the fight though. I beat Golem but got lost afterwards, wandering around right now but cannot find my way - I know there'll be another boss soon but I have no idea where he is. I'm getting extremely annoyed with this dungeon, I'd only entered it because I thought it'd be quick affair but I've been stuck in it for more than an hour with no possibility of exiting to the normal world and perhaps two more difficult opponents to beat before I can go back to surface. I won't ever enter dungeon without looking up the length of it again, I just want to wander around and explore now to boost up my character!