Channeler

Since ancient times, channelers have been used by mages to extract magic from imbued objects. The oldest recovered channeler is an amulet presumably worn by the Great Magus Avamorn, who lived circa 3,000 years ago. The amulet is on display in the Garyialan Royal Museum, might you be interested to see it for yourself.

— Ordall Marvo Nisent, realm guide

When manipulating magic, mages often use a channeler to prevent magic passing through their own body, since this is extremely dangerous and can lead to death. The most common channeler used nowadays is a heart stone. A more ancient and nowadays less often used channeler is a companion. 

Heart Stone

Heart stones are, interestingly, objects imbued with magic. Its ability to channel magic can be activated by a mage. Mages use heart stones to pass magic through when transferring or transforming magic. Few gifted mages are even capable of storing magic in heart stones.
Over time, heart stones lose their potency, and a mage should be cautious to acquire a new one before the old one completely dies. Dead heart stones are nothing more than pretty decoration, but many mages keep them as memorabilia nonetheless.

The duration of life of a heart stone depends on multiple factors including size, origin and frequency of use, and can range from merely one to almost a hundred years. The exact duration is not easily predicted, but a well-trained mage is able to feel it is dying: at the end of its life, gathering magic in a heart stone becomes harder and accidental passage through the mage can occur, with death as a possible result.

Common Heart Stones

Several types of heart stones exist. The different types differ in their origination, however in their functioning they are all the same. Unlike the name suggests, heart stones are not always stones.
In northern Namda they are in fact seeds the size of pebbles harvested from the okaplan fruit. Only once a decennium does the okaplan shrub flower and rarely bears more than ten fruits with seeds worthy of channelers. Several attempts have been made to cultivate the plant and increase yield, but to no avail. Instead, the excess okaplan fruits grown are used to make delicious okaplan jam.

In southern Fergel, heart stones are also harvested from fruit. The liben tree is said to grow exactly in the centre of the Lopindali jungle. The Lopind people view the tree as the spiritual centre of life, and its fruits are only given to the tribal head and healer women.

Most commonly throughout Odezia, heart stones are harvested from the bellies of Great Beasts. While this way of acquiring a heart stone can be one of the most dangerous endeavours depending on your fighting skills, it can also be the most fruitful one. A single beast usually contains several stones, with an average of eight. The largest batch of heart stones obtained from a Great Beast amounts a total of fifty-six stones. However, thirty-two men and women lost their lives fighting this beast called Disaz.

Avamorn’s amulet contained a heart stone likely harvested from a fire toad. The actual heart stone has been removed from Avamorn’s amulet and replaced by a fire opal. The real heart stone is kept safely by the Magi Council.

— Ordall Marvo Nisent, realm guide

Companion

Passing magic through oneself does not always lead to death, however the risk is extremely high. Before the general use of heart stones, mages attempted extraction of magic by passing it through themselves anyways. Soon, mages got themselves what they called companions. Companions are animals through which magic is passed. Well-trained mages are able to keep their companion alive for a while, however the companion will likely die in the end. Because of the inevitable death of the companion, use of a companion is also known as sacrificial mysticism.
The type of animal used as a companion greatly determines potency and chance of surviving the passing through of magic. Some mages prefer easily breedable animals such as rodents and birds. These kinds of animals will likely die after one to ten extractions, with an exception of the bespeckled raven. This rare bird is well known for not wanting to die, and thus, if you are able to find and befriend it, the perfect companion. Other mages prefer animals such as amphibians, which are more resistant to the negative side effects of the passing through of magic.
The extent to which magic can be extracted using a companion is less than when using a heart stone. More magic can be extracted and subsequently transformed or transferred by using a heart stone as channeler, simply because there is no risk of death.
Nowadays, many developed societies view the use of a companion as ethically inappropriate, whereas in rural areas and areas where heart stones are rare it is still common practice. Truly unethical, and widely agreed upon as forbidden, is the use of people as companions. Throughout history, there have been magi who have experimented with the use of different types of companions, including people.
Only several small tribes in the interior of the Mardanni Mountains still practise mortal sacrificial mysticism.