There are a few creatures with multiple heads in Dungeons & Dragons. The Ettin is a two headed giant. The Hydra usually starts with five heads and gets messier from there. Tiamat, an evil dragon goddess, also carries five heads.
The Runespoor is therefore not an impossible D&D monster, but the fact that the heads are so different requires some extra thought. The Ettin heads are often very different personalities but do not perform different functions that would effect their stats. The hydra heads all have a straightforward chomp. The Tiamat heads have unique breath weapons but, again, that’s where the complications end.
The Runespoor heads do very particular things, with a distinct personality. On top of that, Fantastic Beasts specifies that the creature often kills one of its own heads. This snake is an odd duck.
There is probably an easier way to convert the Runespoor for D&D play. There’s definitely a more complicated version. Each head could have its own stat block and abilities, or you could simplify it right down and only have slightly different attacks.
Nevertheless, with what I’ve made here, you get the distinct personalities of each head building into the attacks. Having the Critical Head attack separately, for example, makes the creature deadly enough but also shows that the three heads cannot work together.
Also, having the heads attack like this means that the challenge rating is largely unaffected should you wish for the creature to show up missing the annoying head (as described in fantastic beasts). Part of the creatures challenge rating is based on damage per round, and I’ve worked it so that the two heads do similar harm to the Critical Head. It technically knocks on the door of Challenge Rating 2 with the hit point loss, so you could knock 300xp of the award you give your players. If you’re feeling mean.
Either way, this would make for a very interesting low-tier fight. If the heroes hit that 25 hit point mark, you could allow them to choose what head they want to lop off. Do they want to take out the brainy cranium, or severe the head keeping their minds from being overcome by charm spells?
If the quest was to tame a creature like this (perhaps for a patron who’s a little too close to the dark arts, wanting to impress their friends), then a mid/high level part will actually have to pull their punches on the Runespoor, or they risk partly destroying the beast and their pay check.
As a side note, the ‘reactive heads’ feature is always a fun trait for the DM. Seasoned players of the game know that everyone gets a reactive, ‘opportunity attack’ every round of combat. Flee from a fight and risk an attack. Less players will be aware that some creatures get extra reactions, and will turn to flee to discover a nasty surprise.
Thank You For Reading
All the Fantastic Beasts are being converted to D&D monsters. They are right here!