There have been many requests for details, so here are the details as requested. These are more detailed explainations of their potential magical abilities, how they are put into practice is up to you, as well as other skills. Keep in mind that these are the broadest sense of the types of magic each magic user has, you will not likely be able to do everything on this list, otherwise you'd be too powerful. Enjoy. ^_^
Warlock- This type of magic user specializes in hexes, curses and reality manipulation. A hex is controlling another person's luck by means of a specific trigger. (If such and such is the case, such and such bad luck will happen). A curse is a broad spectrum negative effect that can debilitate a person. (Causing blindness, weakness, disease, clumsiness, etc.) Reality manipulation is the ability to change the laws of the universe temporarily. (Reversing gravity, regenerating, enhancing physical characteristics, etc.)
Druid- The druid has the ability to bend the will of animals and plants to his own. He can communicate with all kinds of plant and animal life, draw on their characteristics to enhance himself, or even transform himself into them. Some examples of non traditional druidism that is possible, tree walking(teleporting from tree to tree by walking through them), shooting large thorns from the palms, exuding poisonous from the skin, blending in with surroundings, etc.
Necromancer- The necromancer specializes in creating and controlling all manner of undead. He creates undead by infusing his will into dead matter, then infusing also whatever components are required for that sort of undead. For example, if he simply pours his will into a dead body, he gets a generic shuffling zombie. If he pours his will into a body along with vampire blood, he creates a vampire, and so on. He can automatically control any undead he creates, though these kinds of undead are limited. he can communicate with and enslave many kinds of undead spirits. He does this by contesting the will of the spirit with his own will and if he wins they are forever enslaved. Bear in mind that not all spirits are undead. Here is a list of undead that can be created. Zombies, ghouls, revenants, vampires, lichs, skeletons. Here is a list of spirits that can be enslaved. Ghosts, banshees, wraiths, spectres, phantoms. The Necromancer can also draw life and strength from his creations, extending his own life and infusing his will to be able to create more undead. The more creations he controls, the more powerful he becomes.
Summoner- The summoner specializes in summoning and enslaving demons, devils, and other ethereal beings. These beings are controlled by the will of the summoner, though they have minds of their own. Once enslaved, they cannot escape unless the summoner dies or they are released by the summoner. No enslaved entity is capable of disobeying the summoner, nor causing him any sort of harm, either directly or indirectly. Every task that is set to them must be completed to the best of their abilities. Examples of ethereal beings that can be bound, djinn, faeries, elves, spriggans, dryads, naiads, etc.
Seer- The seer uses many different forms of divination to see the future, the present, and the past both specifically and in broad terms. There are many sorts of divination, most seers can do many of them. Tarot cards are focused on one person besides the seer, only seeing the future. Runes are focused on broad spectrum questions. Scrying is seeing afar through a calm pool of water, a flame, a mirror, or a crystal. Visions are flashes of present or future events while awake. Dreams are visions while asleep. Stargazing gives a broad sense of the future that is held for the caster or the world in general. Clairvoyance is focused on an object or person by touch, and can read their past and the emotions associated with them. Tea leaves focus on a specific person, seeing past, spiritual state, and future.
Enchanter- The enchanter specializes in enchanting and illusion. Enchanting is only ever focused on objects, instilling them with magical abilities, powers and effects. The enchantment is always more powerful if applied during creation. (What constitutes creation time depends on whether the object was permanently changed, as well as the nature of the object. For example, weapons or armor's creation time is always when it was first forged or put together. However, a written work's creation time is when the words were written, now when the paper was made.) The enchanter infuses the desired effect through emotion and willpower. The stronger the emotion and will of the caster, the stronger the enchantment. Illusions are images that are cast on the minds of human beings that can affect what they hear, see, smell, taste or even, in case of the strongest illusions, feel. The more powerful the will of the enchanter, the more believable the illusion. Illusions will only ever work on those who do not know it is an illusion. To that effect, illusions that would cause active harm if they were real will actually cause harm if the subject believes it to be real. For example, if an illusory tiger slashes at someone who believes it is real, they will actually feel the pain and even gain the wounds. Illusions are just as useful for covering up actual threats as for creating false ones. These are much harder to disprove, and since the danger is real, cannot be avoided by disbelieving. For example, if someone believes the road is clear but the enchanter has covered a ledge that drops off the mountain, it doesn't matter whether you know the illusion is there or not, you will not be able to cross.
