I'm DMing a Tomb of Annihilation-based campaign and we're using Meat Grinder Mode (DC for Death saves is 15).
In the answer to this question, the probabilities of survival are discussed.
This is all fine, however, I have a different problem. I want some monsters to attack downed unconscious party members (sometimes).
As an example, in the last session, the party rogue moved 80 ft. away from the party after encountering a pack of deinonychus on the hunt and fought with two stragglers. They dropped her unconscious and I judged that they would start eating her, since the rest of the battle was far away. She failed a death save, and, since she was unconscious, the next attack* against her was an auto critical which resulted in her getting two death save failures and dying immediately.
*Initiative was such that it was dino (attacked the rogue, downed her), rogue (failed death save), dino (killed her with the auto crit).
I understand that this is the 5e implementation of a coup de grace. However, I would like to give my players a bit more of a chance when downed and attacked, so the rest of the party can at least try to save their companion. But this only works if the player has a higher chance of being able to survive at least a single attack when downed.
I see two obvious solutions:
Attacks vs downed creatures don't auto crit
Players get more death saves (5?) (so they have a higher probability to survive the first auto-crit)
And there are probably better solutions that I didn't think of.
What is the best mechanical solution to this problem with the constraints that:
- Meat Grinder mode is active, so probabilities of dying without being attacked should be higher than 50% (but don't need to be exactly the same)
- Least interference with other rules
- Attacks vs downed are still very dangerous and a strong signal that the downed creatures needs to be saved right now by the party
A good answer should contain the exact mechanics to solve the problem and a short discussion of the probabilities involved. I am looking for mechanics for my perceived problem, not for a discussion focused on minutiae of the example situation. That is, the answer should focus on attacks during death saves, not on dinosaur behaviour or the rogue's tactical errors.