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Faith is new "profession", faith allows to choose your religion, and gods grant you buffs and abilities. example: worshiping dragons may grant you dragonspawn form for movement. Some gods are for especially designed for some classes, like tribal leatherworking for druids. Ancients (Agammaggan/Goldrinn) for warriors and Elune and Light for priests. You gain faith skill when sanctifying items to gods(resembles disenchanting). You can make consumables like with alchemy. example: mix holy dust and obsidian table, you create sacret table of Elune. When you use it, you gain buff, like books in Karazhan, change to deal x more damage, or summon assisting spirit.

Some may find Religion as profession technically difficult, bt its not new in MMORPGHs,even in Everquest 2 there were similar religion system, and different religios are already established part of warcraft universe.

Each religion buffs different things. Last and most powerfull buffs may change your form and gain new abilities. You can have many religions at the same time, like (one of the spesializions) Good Faith: Light, Elune, Nature Worship. Neutral Religion: Ancients, Loa, ect.

Faiths:

• Elune = Healing buffs, may also call stars from sky.
• Loa = Able to channel loa, and turn into incarnation of Primal God for movement. Also has some healing buffs.
• Ancients = Buffs strenght and toughtness.
• Forgotten Shadow = Become Shadow ascendant, mages Invisibility like ability. Buffs damage spells.
• Old Gods = Calls unspeakable minions of Old Gods from depths of earth. Has CCs like fear and coma.
• The Light = Strong healing buffs, increased damage agains demons and undeads. Divine Ascension spell which is like Moonkin but for healers.
• Sect of the Dragons = Damage buffs and may gain dragonspawn form for movement.
• Ancestral worship = You may call spirits of ancestors to aid you in battle. Neutral religion, both damage and healing buffs.
• Nature Worship = Support religion.
• Mystery of the Makers = Support religion too, you may turn into Avatar.
• Cult of the Burning Legion/Demon worship = damage religion, may turn into fel form for movement. Works bit like Solid Stone Statue, summons Demon who channels his own felblood to you.