Sphere was a term that was short for "sphere of influence" in second edition D&D (also known as AD&D). Each deity had a set of spheres of influence in which they were interested and which they embodied. Priests of a deity had access to the spells in that deity's spheres. Some deities provided only limited access (called minor access) to certain spheres and full access (called major access) to others.[1][2] Also, the Elemental sphere was subdivided into Elemental Air, Earth, Fire, and Water spheres.[3] The "All" sphere was available to every faith.[1][4]

Originally, there were sixteen spheres: All, Animal, Astral, Charm, Combat, Creation, Divination, Elemental, Guardian, Healing, Necromantic, Plant, Protection, Summoning, Sun, and Weather.[1][2] Eventually, eight new spheres were introduced: Chaos, Law, Numbers, Thought, Time, Travelers, War, and Wards.[5]

Maztican deities granted access to two unique spheres called hishna and pluma, but in return never gave their followers the Necromantic and Summoning spheres.[6][7]

Spells by Priest Sphere (2nd ed.)
All | Animal | Astral | Chaos | Charm | Combat | Creation | Divination | Elemental | Elem. Air | Elem. Earth | Elem. Fire | Elem. Water | Guardian | Healing | Law | Necromantic | Numbers | Plant | Protection | Summoning | Sun | Thought | Time | Travelers | War | Wards | Weather