There are troll mutants with this. Tyranny of Dragons has one in chapter 7, along with details shared below…
FOUR-ARMED TROLL
Sometimes when a troll loses a limb, it regenerates two limbs to replace the one it lost. This can result in trolls with multiple arms. A four-armed troll uses the troll stat block, except that it is a challenge rating 6 monster (2,300 XP) and has the following action instead of the troll’s normal Multiattack action:
Multiattack. The troll attacks five times, once with its bite and four times with its claws. If two or more claws hit the same target, the troll rends the target, dealing an extra 2d6 slashing damage.
imagine hydra affecting every body part.
lose a finger in an accident, 3 more grow. lose a leg, 3 grow.
it would be so hard to buy shirts and trousers.
There are troll mutants with this. Tyranny of Dragons has one in chapter 7, along with details shared below…
such a beast would make a great source of endless meat for a ever growing community! Would be a nightmare to build a cage for though
I’m pretty sure you need to eat more to get the energy and protein to regrow.
the hydra parts grow magically, no story with a hydra states that the beast has a feast to prepare for the regrowth