I'm DMing a Tomb of Annihilation-based campaign and we're using Meat Grinder Mode (DC for Death saves is 15).
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.