When cast, the speak with monsters spell enables the priest to converse with any type of creature that has any form of communicative ability (including empathic, tactile, pheromonic, etc.). That is, the monster understands, in its own language or equivalent, the intent of what is said to it by the priest and vice versa. The creature thus spoken to is checked by the DM to determine a reaction. All creatures of the same type as that chosen by the priest can likewise understand if they are within range. The priest can speak to different types of creatures during the spell duration, but he must speak separately to each type. The spell lasts for two rounds per caster level.
Notes: Common for clerics and druids (PHB).