Ah.... how I love things like that. If the Players didn't do such things, the game would grow stale.
Near the beginning of my last campaign, 2 years back, the party was in hot pursuit of a very high level spellcaster who was racing to a tower to claim the Big-Bad-Magic-Item-That-Can-Ruin-The-World. He arrived before the Players, but as the players were very close behind him, I decided to adopt a ruse. He took the item, a quick Change Self and some new clothes later, pretended to be a gardner at the place.
The players arrive, corner the "gardner" about anyone that had recently entered. The gardner let them know some magic looking guy had entered recently, but left in frustration shortly before they arrived. I made up some BS about the room holding the Item being magically protected and needing some special key, which the "gardner" told the players the magicy guy probably didn't have.
Everything was going good, the players looked to be buying my ruse, when suddenly one of my players says "I attack him. It's the mage!". Shortly there after the NPC was dead, though he took 2 of the party with him.
The mage they killed was to be a major player in my game for a while, now deceased. And, being that the player who figured out the ruse was of that type, took the mages head and made the skull into a Cod piece which he faithfully wore for years to come.
To his credit, I've known that player for 15 odd years now, and he's always had an "intuition" with my plot lines that stems from knowing me so well. But still. The best laid plans.........
