I recently found myself in a situation where my PHB Beastmaster's animal companion was killed. There were no suitable beasts in the vicinity. As we were partway through a dungeon the party was unwilling to take a several day detour to replace the beast.
After a long rest the rest of the party was full health and ready to continue on but I had no new animal companion. My spells and equipment were optimized around the beast companion so without it over half my damage output was gone.
I ended up spending the rest of the dungeon casting cure wounds as there was little more I could do besides a single hand crossbow shot a turn.
Is there realistically anything I could have done or do Beastmaster rangers have to accept that if their beast companion dies they will be sitting on the sidelines until they can replace it?
DM flatly refused death saves on the animal companion stating it was not a PC.
RAW only; no UA or hand waving.
Best Answer
The Beastmaster Ranger's Ranger's Companion feature states:
This is the only way mentioned of acquiring a new companion, so unfortunately if that is not an option, you will not have a way of getting a new companion. That said, you do have a few options available:
Finding a new companion
There is the locate animals or plants spell:
Preventing the companion from dying:
Suggest to your GM that they allow your animal companions to make death saving throws. This would also give you more time to react once your companion begins to "die", potentially saving them. And it expressly mentioned in the following section:
You could also use the death ward spell:
This spell lasts for eight hours, and so a Cleric/Paladin in your party may cast it for you, otherwise perhaps there is a spell-selling service in your world.