Turn resistance is the ability of certain creatures to avoid being turned. This resistance is expressed as a number that is added to the creature's hit dice both when determining if the creature is turned and when determining if the turn attempt has hit its maximum for total hit dice turned. Turn resistance may be negative, making a creature easier to turn. Turn resistance stacks with itself, with an unknown cap. There is a practical cap, though, as no one can turn a creature whose effective hit dice exceeds the turner's by more than 4. Thus, with the level 40 cap, there is no additional benefit to (net) turn resistance above +44.