If you need to get troll bogeys in Hogwarts Legacy, the easy option should be to just find and kill the monsters to collect them. The difficulty here though can be that most trolls will probably outrank you by a good few levels when you first need to collect them.
However, Hogwarts Legacy troll bogeys are a useful potion ingredient and part of an assignment for Professor Onai. So you will have to find and kill at least one to proceed. The map does show a few troll hotspots, but much like finding Hogwarts Legacy Mandrake locations you have some options and it's not clear what's best. You'll find a lot of trolls in the Forbidden Forest for example, not far from the Ghost of Our Love map location, but there are easier options if you want to get some troll bogeys in Hogwarts Legacy.
Where to find troll bogeys in Hogwarts Legacy
You'll have to find and kill a Troll to collect the bogies when you first need them. There's an easy Troll lair in the north of the Forbidden Forest and another north of Feldcroft. You also fight one at the end of the mission 'The Helm of Urktott' which should be around the same time as the assignment that needs bogeys. You can also buy troll bogeys from J Pippin's Potions in Hogsmeade.
You'll get Professor Onai's assignment the day after completing your first trial. It'll involve testing Depulso on a levitated enemy and collecting troll bogeys. The assignment also specifically says your field guide won't show you where to go, so you'll have to work things out for yourself (otherwise known as googling it, hi!).
There's a few options here, and if you want to multitask you can take on the 'The Helm of Urktott' mission you should also have available. It's not the shortest quest but there will be a troll fight at the end to earn you some bogeys. And, if you play it right, you can get the other enemies you encounter here to fight the monster for you. If you get lucky they might take it out completely for you but at the worst they'll weaken it for you.
If you want to just go straight to a troll lair locations there are some easy options you can find fast - there is a troll lair in the northern end of the Forbidden Forest, with a Forest Troll you can fight to get some some bogeys:
There's also another troll lair north of Feldcroft with a River troll you can take out as well:
You can also buy troll bogeys from J Pippin's Potions in Hogsmeade although this is probably your best option post assignment when you need them for general potion making.
You can find J Pippin's Potions here in Hogsmeade:
Hopefully, that should sort out all your troll bogey needs in Hogwarts Legacy, whether for Professor Onai's assignment or just general potions like Invisibility.
The release of Hogwarts Legacy has been the subject of criticism and debate due to J.K. Rowling's public stance on gender identity, which continues to challenge the inclusivity at the heart of the Harry Potter community. Here is our explainer on the Hogwarts Legacy controversy.
