Distorted Echoes

Once in a while, all the shards of something lost gather together and become a ghost resembling the original either in appearance, meaning, or both. For example, a dog trained to track something dies, and the human who trained them feels like they lost their best friend. Years later, someone in is trying to track something here in the premises, and accidentally triggers those shards and they form a tracking dog with the same look and skills than the real one. If, instead, the shards were triggered by someon who needs a friend but he allergic to dogs, then the ghost will be a friendly lizard pet.
That's what we call an echo, and it can take any form and have all sort of effects. They are extremely complex and rare.
People often want that. "I don't care if you can't give my love one back, the echo of them will be enough". "A magic armor is just as good as being really resistant, it's all the same to me". Sometimes, they are allowed to try to get it. They are to collect the shards, and their emotions do the rest. It goes just fine.
But if someone makes a mistake and allows a client in denial to try this, or if they find the shards by accident, they might end up trying to rebuild the real unrecoverable thing, and that tends to end horribly.
The ghosts resulting from that are grotesque versions of what the person loved or needed. Curses instead of blessings. Obsession instead of love. The shapeless ones need to be removed forcefully for a person, breaking them into shards again.
When they want to recover a living being is... worse. Rabid or agonizing living beings, contorting in horrible ways to walk besides the person who can't stand their sight.
The most dangerours ones are exiled almost as they are created, since there are plenty of spells keeping the worst dangers away from the public areas. But if the person is in an area that is not usually visited by clients, or if they aren't violent in any way, they might stay there. As their owner escapes them or chase them away, these distorted echoes continue to wander by the premises and it's not rare for them to stalk people they met by coincidence.

Original image by kalhh

If you ever notice a shy awful ghost, not a living creature but certainly more than a thing, quietly following after you, they are most likely to be harmless and lonely.
Which doesn't mean you should befriend them. It's usually okay do it, especially if you meet them in the path, but we get it if you are too irked to even consider it. Besides, there is still the slight chance that a barrier has failed, and you are facing a dangerous being.
If you encounter one in the forest, it's a 50/50 gamble. They might be very dangerours for you in particular even if they hadn't been a danger for other kinds of people, or they might be somehow unaffected by barriers which means there is also a high chance that your Beat won't protect you from them either. But if they are nice, you might use their help to survive in the forest.
That said, I always recommend clients to stay away from anything and everything when they are on their own and, even more important, to not travel alone in this world. Always stay with your host and follow their instructions, please!