Conjurers are offensive spellcasters who specialize in violent and volatile Conjurations. Relative to other magical backgrounds (such as the Wizard), they begin the game with a lower general Spellcasting skill, but have a higher Conjurations skill to compensate.
Some species may receive different items based on their unique restrictions.
These are adjusted by your species' aptitudes.
The Conjurer starting book contains a variety of unusual, pure Conjurations attack spells. Searing Ray is an excellent follow up to Magic Dart, very MP efficient. Dazzling Spray is a weak area of effect spell, but blinding enemies does reduce their ranged attack abilities significantly. All of the later spells are useful in their own ways for an offensive caster.
While these spells are all effective, they tend to deal less damage than their elemental counterparts. Still, the fact that they affect all opponents, regardless of resistances, makes them reliable and saves you from suddenly encountering a foe you just can't deal with. When you do find some elemental magic sources, your early training in Conjurations will help you get those spells online quickly.
Prior to 0.9, their starting spell book was different, most notably lacking Mephitic Cloud.