Avatar literally means “descent, alight, to make one’s appearance”, and refers to the embodiment of the essence of a superhuman being or a deity in another form.
The word also implies to overcome, to remove, to bring down, to cross something. In Hindu traditions, the “crossing or coming down” is symbolism of the divine descent from “eternity into the temporal realm, from unconditioned to the conditioned, from infinitude to finitude”.
When a god has business upon the true Prime Material Plane, he must send an avatar. An avatar is simply a manifestation of the god upon the Prime Material Plane.
This manifestation is not nearly as powerful as the god himself, and is merely a projection of the god’s power to the Prime Material Plane.
Always remember, there is great difference between the god and the avatar.
The avatar embodies just a small portion of the god’s power.
Unlike the god himself, an avatar can be destroyed, which is never looked upon kindly by the true god, and often results in some sort of divine retribution.
Although avatars may take many different forms, the number that can be created and the frequency with which they may be replaced depends upon the god’s stature – Greater God, Intermediate God, Lesser God, Demigod.
Often, avatars possess magic items of incredible power.
Unless stated otherwise, these items always teleport back to the god when the avatar is destroyed.
Avatars are unaffected by the restrictions which apply to normal characters.
For example, they often have attribute scores over 18, can be of any class without regard to alignment, dual- or multi-class restrictions, and can even possess a character class while in animal form.
In order to reflect their supernatural natures, however, their statistics are presented more in a monster type format than in that of a character.
Class
Each avatar will not include the special traits of the class it possesses, but yes, it will include the proficiency bonus; if the avatar possesses more than one class, proficiency bonus will stack. It is up to the Dungeon Master to add a proper combination of class traits to complete the avatar abilities.
Spells
Each avatar will not come with the list of memorized spells, but yes will come with an indication of each class and level the avatar possesses. It will be up to the Dungeon Master compile a proper list of memorized spells.
Weapons & Armors
An avatar is proficient with any armor or weapon, no matter the class it possesses; however most avatar yields a favored weapon and wear a favored armor.
Skills
An avatar is proficient in any skill and can add the proficiency bonus granted by each class it possesses.
Hit Points
An avatar has maximum hit points per hit die, and receive hit points from the higher class it possesses.
Saving Throws
An avatar is proficient in any saving throw.