Quote Originally Posted by Urpriest View Post
See, custom monsters are different in that as the DM you can tailor them to the players capabilities and fears. You can make sure that, given however cautious the players happen to be, they will have enough time to figure it out, and you can make sure that the monster's appearance is such that they will be inspired to exercise caution. Plenty of published monsters don't have those attributes.
Actually, I usually ambush pcs with near-death experiences involving mistaken identity early on, since murder-mystery stuff really only works at low levels and is among my favorite setups for an adventure. "Look! the corpse bears wounds from the bite of a wolf." I think you can see where this is going; it wasn't the wolf.

At some point, a seemingly interaction encounter goes wrong, or in the middle of the fight with the enemy soldier, a hideous parasitic demon explodes from it's torso. It's not that I don't allow Knowledge checks. I just limit them to what is observable in the monster at hand, and I will occasionally make said appearances or behaviors misleading. Once the real fight is revealed, then I guess Knowledge checks are fine, though I do have a personal soft spot for aiming at the party weak spots, as much to make them aware of their weakness as to challenge them in combat. Steel tested in fire blah blah.