Practical and Divine Theology Meet

{All biblical extracts are taken from a NAS}
Clerics are currently a rare breed of magician, despite the fact that at one point in history they were the most abundant religious rank available. The art of Clerical magic has long been lost to the belief that all magics are evil devices of Satan. In truth, the practice of non-demonic magic by priests and clerics was widely supported by all people, both Churchmen and Laymen, until the publication of the Malleus Maleficarum in 1486. With that publication, written by Kramer and Sprenger (two Dominican priests), the whole magical community was turned upside down. People (mostly) ceased using the demonic magics and began investing all of their time in the natural magics. This tradition -- the use of natural and divine magics -- lives on in Clerics.
First, so as to understand the basis of power for the Cleric, one must examine their lifestyle and philosophy. The Cleric must possess three attributes in order to use their magics. Firstly, a Cleric must be spiritually ordained in Christ. This does not imply that an earthly second part be present, but rather that a belief in the saving power of Jesus Christ and the repentance of sins are parts of the Cleric's life. Secondly, a Cleric must aspire to spiritual and moral perfection in everyday life, based on 1 Thessalonians 4:2 ".. that each of you know how to possess his own vessel in sanctification and honour." As a Cleric, you must "show yourself to be an example of good deeds with purity in doctrine; dignified, [and] sound in speech which is beyond reproach in order that the opponent may be put to shame, having nothing bad to say". (Titus 2:7,8). A Cleric lives their life in holiness, always striving to be of the best moral and spiritual character that they can be. A day filled with prayer and solemn holiness is typical for a true Cleric.
Clerics are very familiar with the bible, both old and new testament, and lead an exemplary life of devotion to God and of work befitting a servant of Christ. The benefits of this life style are manifold; some manifest themselves in the afterlife, and some manifest themselves in this life. The benefits reaped in this life are the abilities of Clerical magic. Clerics are famous for a few abilities, both through experience and through legend, that set them apart from the other caster types. Clerics, historically, have been attributed the powers of healing, magic immunity, exorcism, and calling divine intervention.
Healing for a Cleric, unlike a standard Healer, does not involve a knowledge of the ethereal body. For a Cleric, the work is done by the Holy Spirit. The Holy Spirit is that spiritual part of the Cleric which indwells them at the time of their
salvation. Upon willing an injured person to be revived in the name of Jesus Christ (through which a Cleric receives any and all of their power), the Holy Spirit is the power which takes over and begins to work the revivification process in a target. Done with true compassion, a solid faith, and (most importantly) a holy purpose, a Cleric's healing is often instantaneous.
Another rare but common power of the Cleric is their seeming ability to ignore the effects of many spells. While not constituting a total immunity, the magical immunity of a prayerful Cleric is a common attribute. The stronger the Cleric is in their spiritual and moral walk with God, the purer their life and the stronger their prayers, the higher their immunity to direct magic seems.
Exorcism is a power that was often used by medieval Clerics, and continues to be a common function of modern Clerics. The demons which have been summoned by a Conjurer often can be dislodged from the earth sphere by the holy presence of a Cleric. Using devices such as Holy Water, a Cleric can banish unwanted demons. Sometimes, though not often, the sheer presence of a holy servant of God, such as a dedicated Cleric, is able to frighten a demon into submission. Clerics must be fondly familiar with the Bible to be able to banish a demon but, with enough practice, can perform such a task with a holy strength.
The last and most notable ability of a Cleric is that of calling divine intervention. This is by far the most powerful ability that a Cleric can call on. It ithe power to call God himself to directly act in a situation, thereby often turning incredibly poor odds in the favour of the Cleric's holy purpose. Impossible situations commonly turn themselves to the Cleric's favour when divine intervention is called. Angels may assist the Cleric in a infinite variety of ways, depending on the situation, and occasionally God himself intervenes on behalf of the Cleric to sort matters out with the power of divinity.