This is a chapter recovered from the diary of the legendary Eira, an explorer of the outer planes of the world, who dedicated himself to discovering all its mysteries until his sudden disappearance.

**As it was partially found, any referring information is welcome.

Recovered entry 01 Felhounds

They got his name from ancient forest villagers in anglo-saxon areas, its name came from the belief they were dogs that belonged to a demon, no less reasonable idea, they´re actually empty undead vessels, who got their magic energy stolen.
They are usually represented as canines with black hair, pointed ears, red eyes and spiral horns; it is also said that they can reach measures of up to 3 meters long and 1 high, as well as run at high speeds for short periods of time. Some rumors mention his ability to cast simple spells, such as to empower himself, become invisible and confuse his prey. Even so they do not have unlimited magical energy, they need to steal it as parasites from other living beings to survive. They can live an unlimited amount of time and heal any wound as long as they remain in some way without draining their energy reserves, otherwise they die leaving a cloud of black dust, which if breathed in, allows them to regenerate from the energy stealed from the living being who inhaled them.
Just as any undead are unable to reproduce among themselves, even so they often try frequently and they apparently get pleasure from doing it.
As you may have guessed, they do not receive nutrients from meat or any other physical food but it has no negative effect on them when consuming it, they can only maintain themselves by draining magical energy, and this is achieved in two ways, by extracting them with their sharp teeth or by forming pacts to anyone willing to pay their price.
When they make a pact, they change their shape to become an identical twin of their master, learning their language and customs, while maintaining their own skills and sometimes getting new ones.
Their diet is based mainly on wild creatures but they will not avoid feeding on humans with higher amounts of energy.
In some strange cases, they have formed pacts with newborns, becoming human newborns themselves, forgetting their bestial nature and even believing themselves to be human, showing very little magical ability and manifesting any injury that their twin receives. and getting severely ill when a brother strays too far, so they end up developing an obsession with staying close to their twin otherwise they present intense physical pain. Once reaching adulthood he recovers his memories and becomes a loyal servant of his until then brother.
Historically they have been trained and used by some kingdoms at war to eliminate magical defenses, repel attacks on the most important cities as well as to identify children with exceptional talents.
Professional hunters say that the best way to protect children from an attack by felhounds is to place a rune to absorb magic energy on their arm, working as a battery, the beast would only be attracted to the armband, they have even paid the children's parents to make them wear the bracelets, once fully charged they pick them up and use them to catch them.
Even so, it is not advisable to eliminate their entire population since they serve to keep other more dangerous creatures out of the forests.
So if you are being chased by a felhound, there are some tips that you should take into account.
1. Do not use magic attacks, enchanted weapons, any type of magic, as they will absorb almost all the energy of the attack and use it to regenerate.
2. Use any unenchanted weapon or any non-magical item, they are usually incredibly fragile against physical damage.
3. If there is no other option and you have enough energy, offer them a pact, but this should be the last option since you cannot remove any pact with them.
4. If you already have a pact with any of them, probably others will try to make a pact with you, but if you exceed your capacity they will turn against you and turn you into one of them.and you will be condemned for all eternity to parasitize other beings alive.