A priest is a part of the original MMORPG trio, the Priest has been a fundamental aspect of any group. The priest represents the healing and durability aspect of any party. Of course, in World of Warcraft, priests have evolved quite a bit more from being just a healer. They possess the strongest Magic Dispel out of all the classes, and they have a plethora of Power Word, Shadow Word and Holy Word abilities to perform various task, focused on damage reduction and absorption, shadow damage and effective healing. A priest has three sub-specialties: A Discipline priest focuses on strong shields and tremendously increasing the effectiveness of his Power Word: Shield spell, while the Holy Priest focuses on pure healing output. A Shadow priest literally melts face with his powerful damage over time and direct damage spells.
Of course, a good WoW Priest Keybinding layout focuses on the spec that the priest selects, but also allows easy access to other schools and abilities, because the most successful priests know when to shift from being a pure healer to a more utility based role, and even go as far as cast some Holy Fire or even Shadow based spells to help out with damage.
A Discipline Priest’s Keybinding setup focuses on easy access to the discipline specific spells, such as Penance, Power Word: Shield and Pain Suppression. The power that the Discipline Priest gets from the talent synergy with Power Word: Shield makes the priest a formidable healer whenever a single target is taking damage or multiple targets are taking damage as the power of Prayer of Mending and Renew allows the priest to heal many people at once. Of course, often the situation calls for usage of other spells such as Holy Fire or Smite or even Mind Spike.
A Holy Priest is the epitome of healing output. Whether it is healing a tank, a raid or any combination, the Holy Priest should exceed at the role, as long as his holy priest keybindings are good enough to adapt. The usage of Heal, Greater Heal and Renew, along with Prayer of Healing turn the priest into a Heal Per Second machine, while the synergy with Chakra and Holy Word spells allow a priest to change his playstyle to fit the situation that the group needs most.
A Shadow Priest is oriented on dishing damage to the enemy, by maintaining Vampiric Touch, Shadow Word: Pain and Devouring Plague while unleashing terrible face melting with Mind Flay. The synergy of Mind Flay with Shadow Fiend and Mind Blast calls for interesting Keybindings from the Shadow Priest. The power of the Shadow Priest in PvP settings lies in the defensive dispel ability — they are the only class that can dispel magic debuffs on the party that’s not a healer. Of course, in a pinch the healing power outside of Shadow Form is nothing to laugh at either, it’s just not quite as powerful as that of the dedicated Discipline and Holy trees.