As far as the battle being too tough, its just something this guy does. The week after this, two party members (level 4) were going to harass some low level vampire that we had defeated. The DM didn’t want this players going in that direction for whatever reason, so he attacked them with a dread wraith.
As far as the Vrocks motivation. The DM claimed they were hungry so when I went down he bit my head. But that raised so many questions.
If you put food in front of a staving dog, obviously he will go at it. But does his hunger cause him to continue eating while you punch and kick him. I assume he would take the time to bite you before going back to his meal.
Even so, the motivation of the Vrock being hungry didn’t make sense. He didn’t eat me, he did a coup de grace by biting my head. Then he went on to kill, and coup, one more character. If he were that desperate for food, why didn’t he just sit there and eat me, for grab me and fly off. Either way, I would have been dead, but at least it would have made sense.