Shamanism is one of the absolute hardest things to properly translate, because everyone wants to make sure the flavor is correct, which is great. The question is; what does Shamansim taste like? Is it chunky, with lots of feats? Is it deep and relaxing, with domains? Is it friendly, and deal with animals? Answer: None of the above.
There was a long volley between two peeps about whether or not you can pinch-hit Shamanism. Sure, you could. Whether you focused on Druidism, to bring out the Totemic side, or Clerics, to bring out the philosopher side, you can take either class and say "This is a Shaman for my purposes." However, my suggestion would be to do a fresh build (yeah, I'm going there) and, without completely reinventing the wheel, develop a set of core abilities that would allow the class flexibility without stepping on the toes of the other primary casters.
So here's a model (literally off the top of my head, that may or may not resemble what's come before) which y'all can feel free to borrow, rip, tear and assist in defining. My two cents sound like this when they hit the concrete:
Class: Shaman (Divine based Spellcaster Hybrid)
Hit Dice: d8. Shamanists spend much of their lives enduring self-induced trials in an attempt to force their minds and souls into a greater state of oneness with the cosmos. They are tough, and can take serious punishment.
Skill Points at 1st Level: 4xINT modifier; the bulk of a Shaman's power comes from the spirits they call and channel; far more time is spent in reflection and communion than study and lore. However, they must know certain things to fulfill their role as healer and apothecary. The Shaman uses the Druid skill list. Includes Knowledge: The Planes.
BAB: Average Progression
Saves: All Good. Shaman are trained early on when fighting spirits and their manifestations that swiftness, toughness and strong will are all required to survive.
Armor: Shaman Dance and Rituals require freedom of movement. They also believe that wearing heavier armors interferes with the spirits ability to reach them. As such, Shamans have the Arcane Spell Failure for armor counted against them when Calling Spirits to them.
Spell List: Shaman draw spells from specific domains, not from the standard collection of spells, and may pull spells from those domains only. Each morning, while communing with the Spirit World, the Shaman may select three of her total known domains and gain the benefits of them as a Cleric would. At 5th level and every 5 levels beyond, the Shaman may choose an additional Domain Power each morning that she can utilize.
Domains Known: A shaman begins play with six known domains, and learns a new domain at 3rd level and every 3 levels thereafter. This gives the Shaman flexibility, and forces them to carefully choose their font of power. Shamans use the Sorcerer spells per day table to determine casting ability. A shaman does not need to prepare their spells ahead of time; they know them in their souls, but they must commune with the spirits at a time the Spirit deems appropriate, usually based more on the spirits most active cycle than any alignment. A Bat spirit is active at night; a Wolf spirit hunts during the day.
Here's the part that needs real work (like, hours). Shaman Abilities. Shaman are defined by their association to the Spirit World. Through that communion, they can reach past the mortal world and into another world entirely. This ability is known as Calling. A Shaman's ability to Call is similar to a Clerics ability to Turn; different Callings consume a different number of Call attempts, and a Call is not a guaranteed success.
As far as full blown development of all possible Calls, I'm envisioning something that can be modified for flavor (i.e., which spirit and why?) without pidgeon holing the Shaman into something specifically Native American or Chinese, which is unfair stereo typing. A Shaman would begin play with only a few Calls, and would learn new Calls as they leveled (at a rate of roughly 1/2 lvls, as this is their bread & butter ability).
Call Attempts are Charisma based; the Shaman is putting their soul on the line to ask a Spirit for assistance. A Shaman gets a number of Call Attempts per day equal to their level plus their Charisma modifier. The mechanic I've envisioned would work similarly to the Wilder from the XPH; a class which has the option early on to burn multiple attempts (Calls) to achieve a higher than average result, with each additional Call attempt used raising the difficulty for the check by two, and the number of calls directly related to the math used to determine the final effect.
The check for a successful Call would be: 10 + Call Level + Call Attempts (x2). So, if we say that Call of the Predator is a 1st level Call, and the Shaman has opted to use one Call attempt, then they make a Charisma check equal to a DC 13 (10, plus Call of the Predator (level 1 call) plus one call attempt (2)).
To complete this, we then have multiple options as to how to grow the class. We have a mechanic, we simply need to create Calls in a manner similar to feats. Say, Call of the Predator is level one. Call of the Predator would be level 4, give additional benefits and have Call of the Hunter as a prereq.
Call of the Hunter (level 1): The Shaman channels forth a greater manifestation of the Hunter, granting the ability to Track, the Scent feat, and superior vision (low light, if the shaman has low light vision, its range doubles). The Shaman gains +X on all Survial checks, where X is the number of Call attempts used.
Duration: 10 min/call attempt
Call of the Predator (level 4, Call of the Hunter, min. 2 Call Attempts): The Shaman channels the Spirit of Wolf. He gains a +X circumstance bonus on all Survival checks, and +1/2 X to both Strength and Dexterity. X is the number of call attempts used in Calling forth the spirit into the Shaman's body. He gains all benefits of Call of the Predator, as well as the improvements of Call of the Hunter.
Duration: 10 minutes/Call Attempt
Feats would be simple; Extra Domain, Extra Calling, Improved Duration (spend a call attempt at no charge to the roll, improve duration) and so on.
This is a very rough draft that I'm editing on a small window, so please forgive any errors and build / edit as necessary.
LCpt. Thia Halmades