[RPG] Mechanics of how to kill a hydra

combatdnd-5emonsters

In a session where I was the DM, I made my players fight a hydra. In the end I had to end the battle by stating the hydra became unconscious. It was at 0 hitpoints for a good 4 turns before I made my decision.

I took so long to make my decision because of a statement made in the hydra's information in the monster manual pg. 190

Whenever the hydra takes 25 or more damage in a single
turn, one of its heads dies. If all its heads die, the hydra dies.

So at first I assumed until all the hydra heads fall off it would not die. But my players were unable to kill the heads resulting in the hydra just falling to 0 health without any heads having been killed. If I let them try and cut off all the heads they would never had done it.

In short my question is
What are the different ways to kill a hydra

Best Answer

The rule about all of its heads dying is an exception particular to the hydra. It is not immune to the effects of being defeated when reduced to 0 hp.

If the hydra were immune to defeat at 0 hp, its description would have to say so.