Models with this rule can never refuse a challenge and, if possible, must always issue one. If there are several models with this rule involved in a combat, the controlling player chooses which will issue/accept the challenge.
In addition, if a model with this special rule kills an enemy character or destroys a non-Expendable unit in either close combat, with spells, or through charging/pursuing, immediately make a 2D6 roll on the Eye of the Gods table. If there is more than one character in the unit at the time of the destruction of the enemy unit through pursuit, each character gets to make a separate roll. Once the result of the roll has been determined, make a note on your army roster – that model now has that reward for the rest of the battle. A model can have several rewards, and it can even have the same reward multiple times. If, for any reason, a reward cannot be applied, the result is instead treated as a ‘The Eye Opens’ result. Note that the model itself must cause the last unsaved Wound on an enemy model to claim the kill. If an enemy model suffered multiple Wounds simultaneously, randomise between the sources to determine which caused the final Wound.