Faith is a powerful thing and is duly rewarded from on high... if you are devout enough. Lip-service to the gods can impart certain benefits during combat like reducing damage, increasing your strength or defense, or even sapping your enemy of their abilities.
Praying in combat is considered a free verbal action. While praying in combat, you cannot talk. For all other purposes it acts as if charging a spell or aiming; meaning it takes effect at the start of your next turn and can be interrupted before then by taking damage.
The DC to keep saying your prayers while taking damage is: Base DC + Damage Taken
Prayer is not infinite; you are only granted so much favor and it drains as it is used. You get 10 Prayer Points to start, then +5 for each skill point in Prayer you spend. Ex: A player with +4 in Prayer gets 10 + (5 x 4) Prayer Points; 20.
Not everyone wants the gods to rule over them, and rightfully reject the idea of praying to them for favor. Do not fear, this does not deny you access to prayers. If your character is Godless, they can beseech the Anima Mundi directly for the same benefits as someone praying to a god.
These are the standard prayers that nearly everyone knows. Because they are common knowledge they are simple and streamlined, making them easy to say in the midst of combat. Their base DC is 10.
Accuracy Enhancing: This is your Incredible Reflexes, Eagle Eye, and Mystic Might. These give you +3 to Attack, Ranged, and Magic respectively.
Damage Enhancing: This is your Ultimate Strength, Overpowering Force, and Overcharge. These give you +3 to your melee, ranged, and magic damage respectively.
Restoring Prayers: This is Rapid Restore, Rapid Heal, and Rapid Renewal. Rapid Restore reduces all debuffs on you by 1 point per round. Rapid Heal gives you 2 health back per round. Rapid Renewal gives you 5 health per round, but is harder to say and maintain. A requirement for Rapid Renewal is +5 Dungeoneering.
Protection Prayers: These are the most powerful prayers that everyone has access to. They can reduce damage from a certain type by 50% from NPC’s and 25% from other Players. Naturally, they’re a bit harder to say under pressure.
Knightly Prayers: These are special prayers only taught to those with special knightly training. They give you +4 to Accuracy and +2 to Damage and Armor Class at the same time.
Retribution: This is a last resort, a sort of curse for your last stand. If you die while saying this prayer, you deal half your remaining Prayer Points in damage to all targets adjacent to you.
Smite: This prayer drains the Prayer Points of your enemy by 5 points per round, plain and simple.
These are profane curses that few people know, and fewer even dare to utter. They require a cursory knowledge of the demonic tongue and are suitably hard to speak in combat. Their base DC is 15.
Sap Curses: These curses drain your opponents abilities, increasing in strength over time. For each round spoken, the enemy suffers -2 to their ability sapped, capping at -6.
Leech Curses: These curses drain your opponents abilities and transfer them to you, increasing in strength over time. For each round spoken, the enemy suffers -2 to their ability sapped, capping at -6.
Deflect Curses: These curses not only protect you from 50% of a type of NPC damage (25% Player Damage), they also reflect 50% (25%) back upon the attacker.
Soul Split: This is a nasty curse that heals you for 10% of the damage you do and drains enemy Prayer Points by 1 for every 5 Damage you do.
Turmoil, Anguish, and Torment: These are the ultimate curses, sapping -2 Accuracy and Defense per round capping at -8 while boosting your Accuracy and Damage by 10%.
Wrath: This is a stronger version of Retribution that hits all enemies for your remaining prayer points in a 5x5 area.
Prayer points do not recharge over time. Spending one hour at an altar restores prayer points fully.
Prayer Potions can be used, restoring 10 points per sip. Prayer Potions can be bought at Paterdomus for 100gp each.