Curse, fear, confuse, etc.. aka what controllers do in mmorpgs. You also get a ghost to fight with you, raising your party count from two to three which helps.
Ghost=tank Chani=healer You=controller/dps
It's your classic Rpg party makeup.
I see so many people say "you mean I can't shoot fireballs out of my hand and set fire to people? Omg guns are better".
Guns are straightforward offense. Voodoo is centered more around defense/security.
Guns are the easy way out. I've played both a lot, and guns do make things easy, just in a different way than voodoo. Guns let you steamroll the game and remove most of the challenge.
Also which you choose affects your story quests too. Guns gets rather boring straightforward fetch quests. Voodoo gets unique quests usually involving taking over someone's mind and being them, which leads to some funny dialogue at times.
Thanks for the notes. I like playing RPGs as a pure mage wherever possible and I've always felt that PB wasn't terribly friendly to mages and I was particularly worried about magic in this game. This helps a little although I'm still skeptical. I like fireballs :-).
I have invested in guns(4), swords(4) and cunning (4), and realized now that maybe I made a mistake, should I skip voodoo and keep on investing in either sword or guns or take on voodoo. Since the game is extremely difficult this time on, I often wonder if you are meant to specialize in only one or two of the skills, not balance them out. :/