I - Rules
(see AOD, p. 8)
A monster with the Dark Prayer ability generates 1 threat for the overlord for every surge it rolls when attacking, instead of for every 2 surges. In addition, the figures gains +1 Range and +1 Damage for each surge rolled when attacking.
II - References
Heroes with the Dark Prayer ability: none.
Monsters with the Dark Prayer ability: Dark Priests.