"All popular selections for this complication! Curses are basically just another combat magic to most people, it is not much friendlier to set someone on fire than to give him a sickness or make him have an accident or give him the nature-hates-him feature or send him to go berserk for a bit. Big draw of the curse format is conditionality - curse a guy to trip over and fall if he says slurs or violates restraining order or something. Attaching other magic to curses lets other things be also conditional. Rank three gets you voodoo dolls. Rank five gets the curse of immortality, which is perhaps heaviest duty out of all forms of immortality, and soups up the voodoo dolls, though for big curses you need full moons at some point in your process.
"Necromancy has combat features mostly redundant for a sorceress - not much better to throw bones at somebody than metal slugs - but also a rank zero effect you would lock out if you restrict it to let witches see ghosts and spirit creatures. Buying ranks would get you talking to dead people as though on the phone at one, sprucing up feral ghosts so they can think straight and go to a nice safe afterlife at two, stick volunteer spirits to constructs so they can go around revenanting at three, by rank five you can be a lich with your soul hidden in an egg or whatever strikes your fancy.
"Consortation gets you demons who will trade favors with you. Many witches use this up to midrank no problem as a magic Craigslist, starting with little six inch imps at rank one - I think these are possibly more useful to tiny witches - on up through foliots, succubi, nabasus, balors, astarothi, all want you to do appropriate classic sin things for their labor, I know a very nice spa staffed with sloth demons who like it when you lie around doing no things. Rank five is only good if you want to give a boss demon a soul at least every month or refinance with also souls in some other configuration. Which I am neutral about you doing. If you do want to do that it's another immortality method, gets you a big whack of more power points or another standard wish but people usually go for the power points one, also you keep your loot if your boss demon should die in some way though they do not do this each Tuesday. Some witches turn into demons their own selves in this way also."