I'm not 100% certain of what you're looking for, but I'll give it my best shot.
A warlock is someone who has a in-born connection to magic, like a Sorceror, but stemming instead from chaotic/evil entities. They don't cast spells, but have "invocations" which are at-will spell-like abilities they can do as many times a day as they want. Most of the invocations are more defensive/utility abilities, except for the ones that change their eldritch blast, which is their other big class feature. Eldritch blast is a ranged touch attack that does 1d6 at 1st and scales upwards from there, with unlimited uses (just like the invocations). They get a handful of invocations that attach status affects/areas/damage types to their blast (which doesn't have a save by default, but which does have to check SR). They have a handful of minor abilities relating to wand-use and some resistances based on their fiendish powers.
I've only seen a Warlock in play at lower levels, but she was a pretty good damage dealer, and with constant See Invisibility, she gave a good bit of help when we were attacked by invisible foes. Also, I'm not sure where, but I saw some write-ups of alternate versions that were powered not by fiendish might, but by faerie/celestial/draconic/other? abilities. If anyone knows what I'm talking about, I'd love to find that write-up again, it was pretty cool.
Is that kinda what you were looking for?