The Isenulf are the white wolves bred to go into battle with the drüskelle. They are said to be larger than normal wolves but highly trained and deadly in a battle against Grisha as they are not affected by Heartrender powers.
The isenulf have been bred by one family near Stenrink for a number of generations. It is a tradition for drüskelle in training to visit the breeding grounds in the Ring of Stones to choose a puppy. Not all drüskelle get an isenulf if there are not enough puppies bred that year. The wolves are paired with the drüskelle as puppies.
If an isenulf is killed, though it is a terrible loss, the drüskelle may train a new wolf if he chooses. If a drüskelle is killed, on the other hand, the isenulf is sent back to the wild, where it roams unaccepted by any pack.
- Crooked Kingdom, page 240-241
- Crooked Kingdom, page 239