One downside of converting Harry Potter critters into D&D monsters is that sometimes you have to make a plainer version of something that is already in place. Trolls exist in Dungeons & Dragons, and they have a fun regenerative ability that makes them a dangerous for at lower levels, whilst also providing to fun moments for the uninitiated:
DM: what do you want to do on your turn?
Player: Wuh? The troll is dead. Why are we still in initiative?
DM: …no reason. Troll: [on the ground, about to regenerate] Tee-hee-hee.
At first glance, the Fantastic Beast troll is a much plainer creature. A big slab of dumb meat. It’s not going to be as fun to tinker with this stat block. However, the fact that they have “prodigious strength” means we have something to distinguish this new version.
Troll, Scandinavian

So we have a troll that has less of the skill and ability of the predecessor, and a lot less brains, but a whole bucket load of physical force to make him a match in terms of Challenge Rating.
Whether you are running a Potter-themed game or not, this would be a good one to throw at your more experienced players. They’ll go in expecting something to claw and nip at them and slowly heal, but instead they’ll get there world rocked by a hefty face-full of greatclub.
For the DM, the low intelligence is definitely something to play into. 6 intelligence is barely above most animals. Whilst a troll that’s lost is temper is a major problem for a low-level party, outwitting the creature at rest is definitely a viable option.
Heck, the one in Philosopher’s Stone just stared at the club above its head and never thought “that’s going to fall on me”.
So when you play these trolls in your game, just remember that the concept of gravity is something that alludes them…
Thank You For Reading
You can find the full list of D&D-ified Fantastic Beasts right here.