Well, today we DM'd a small attempt at the D&D adventure Curse of Strahd. Our players, all of them low level [sub](three level 2 players, one level 3)[/sub] eventually got into a church wherein a vampire spawn had been locked into the cellar. Despite being told that the vampire spawn was down there and being made aware of the fact that it was starved, they decided to enter the cellar. As even a vampire spawn is far beyond the reasonable challenge level for characters of their levels, that in itself is rather foolish.

Then, for some reason, the party's rogue decided to "feed" the vampire by holding his arm over the vampire's mouth and slashing the wrist so it would bleed.

As it turns out, vampires do bite the hands that feed them. In one attack, that character went from full hit points to zero.

A few rounds later and even with the vampire spawn being nerfed somewhat on the spot, first one player died, then soon afterwards a second one. By this time, the third second-level character wisely realized that being upstairs was safer. Naturally, even with the vampire generally rolling poorly and with disadvantage, the third player died. The final player, who had closed the trapdoor to the undercroft with the vampire (and his now-dead friends), fixed the lock magically and ran off.

Not quite a TPK (total party kill) but still close enough. And they would never have been attacked if they had listened to the priest who didn't want them to go down there, or not tried to feed a blood-starved vampire without even considering things like restraining it first.


Lesson the players learned this day? "Don't feed the vampire."


[hider=D&D 5e technical stuff]
A vampire spawn like the one they faced has a challenge rating of 5 and grants 1800 XP if defeated.
The estimated experience threshold for a "deadly" encounter (the hardest listed in the dungeon master's guide) for a character combination like theirs is 1000 XP. 

deadly challenge XP threshold for a second level character is 200
deadly challenge XP threshold for a third level character is 400

Thus their combat would've still been deadly if they had had two extra characters of third level, something they did not. [/hider]

We of course had no choice about letting them down there, as they rolled a natural 20 on persuasion upon the priest to let them go down there.