Voodoo lady of some sort. Not so old, is black and knows many of Runeterra's magical ailments, hexes and visages, and how to alleviate and cure them. Gameplay-wise, I'd imagine her being a Support class.
http://usercontent2.hubimg.com/4667433_f520.jpg http://farm6.static.flickr.com/5323/9176778642_30c2039e9c_m.jpg
She'd understand curses and hexes like it's her first language but does not practice them. She may also be homed in the Kumungo Jungle with her tribe, and so we can assume lenience towards nature and animal kingdoms (e.g Rengar, Zyra, others). LoL's tribes seem to be around Mount Targon somewhere so who knows.. She'd be of neutral alignment whose knowledge and skills may attract those who seek her aid. Ryze may want to learn what she knows for his own quest for knowledge .. but I get the feeling she will be disappointed for his reasons for visiting and conflicting ideas (Ryze misuse magic; old voodoo lady does not).
What Soraka is and her purpose may easily be shared with this old voodoo lady .. but this voodoo lady may not be on any pursuits.
Zilean's ailment, his chrono-displasia magical disease, may be important for him to find this old voodoo lady. Maybe she can help him! This would be a more loving and caring interaction between two characters. This specific story may be very interesting. :)
She may be intrigued by other magics particularly that of which Karma practices. The discipline of Karma wouldn't be the same as this old voodoo lady's but they understand when to not misuse magic. It could be that Karma 'sought an old lady's guidance who lives in the jungle' after the battle from Noxus against Ionia. Karma's magical disciplines were breached during this battle so she may have needed to ..err.. find enlightenment from her recent troubles and knew exactly who could consult her best (because who else can do what old voodoo lady can do?).
How can she know so much? She'd have learned from all travelers who sought old lady's great grandmother, and all that was learned has been recorded and passed through generations in her tribe to this old voodoo lady. Zilean may also have traveled his mind across time and brought back stories of future and past events. All this knowledge of events and magics unknowing of how to practice them would instead be translated to more of a story-telling fascination for immersion and escapism in a jungle world where there's nothing much to stimulate their imaginations without travelers.
What her magic is may actually be the ancient mysteries of Gems incorporated in her adverse abilities. Imagine grinding herbs and minerals with a mortar and pastel. Most of the time she just says the right thing for people but other cases may need those Gems. I suppose Taric and Gragas would pay a visit, too. With this in-mind she has some tolerance for Gem magic as it probably cannot be misused (unless Taric can prove her wrong).
Many other champions who believe in this old voodoo lady may also have sought her consultation. Can you think of who else?
Nidalee's shitty background could be updated with a visual update, too. A black Nidalee could be of this same tribe as this old voodoo lady's tribe. It could be that she sought the old voodoo lady on how she is able to polymorph.
This character has so many connections it could update many champion's backgrounds with it in one scoop.
