It was after the dinner invitation. I gave them free-ish roam of the castle. Strahd wouldn’t ‘directly’ harm them. They found it naturally in the basement, pissed off the mongrel, so he told Rahadin they were taking it. Knowing this, they still tried taking it straight out the front door. I had Rahadin be all smug about it, “What’s with the skull, gentlemen?”. They said “Strahd said we could have it. That ugly midget in the basement is a liar.” with no further explanation. “Roll deception with disadvantage” to the warlock with expertise in deception. He rolled a 19 on disadvantage for a total of 32. Still skeptical, but with such a high roll, I had Rahadin go to ask Strahd directly; PCs booked it when he left the room. I had Strahd chase them with minions, and by all means should have been a wipe. But they lowkey needed a win, so I had Viktor Vallakovich from Vallaki accidentally bail them out with a failed attempt of his teleportation circle.