That is a one part in S that I do remember. It was quite fun to set traps in mid-game just like NotMorgoth said, but I too found them too weak to be useful later. But it definitely is one of the favorite features of S for me (others being that UI, weapon/armor forging and the fact that it feels a lot more "random" than vanilla, some of the monsters you meet you just can't deal with no matter how carefully you plan your trip).
Comment