Theoretically, every action has a particular moment at which it will have its greatest possible effect. Using the arcane mathematics of this spell, the priest can determine the "ideal moment" for any single action in each round that the spell is in effect. This action must be performed by a character other than the priest.
In practice, another character informs the priest of an action he wants to undertake in a round. The priest concentrates on the action, then informs the character when the "correct moment" has come. The character then gains a bonus of 20% (+4 on a d20) to the success of his action. The spell can affect only a single action in a given round. When used in combat, the priest can advise the best moment to initiate an action (affecting initiative) or what moment offers the greatest success in striking (affecting the chance to hit).
If the character seeks advice concerning initiative, he gains a -2 modifier to the initiative roll, but only at the cost of -2 on his chance to hit. Characters who seek the best attack frequently delay their actions. These characters suffer a +1 on their initiative roll but gain a +4 on their chance to hit. The spell cannot affect the amount of damage caused, since the act (striking) has already succeeded at that point.
Characters are not obliged to wait for the moment specified by the priest. For example, a fighter might decide that striking first is more important than gaining +4 to hit. The character can act normally, based on his or her unmodified initiative. The character gains no bonus from the moment spell, and the priest can affect no other action in that round.
Noncombat actions can also benefit from the moment spell. For example, a thief planning to climb a wall may wait to start her climb until the priest informs her that the moment is right. If she waits, she gains a bonus of 20% to her Climb Walls roll (in this case, the bonus is subtracted from her roll).
While concentrating on this spell, the priest can take no other action. A break in the priest's concentration—taking damage in combat, for example—terminates the spell instantly.
The material component is a set of three silver dice, which the priest tosses in his hand while concentrating on the spell. The dice are not consumed in the casting.