Necromancers can summon spirits to this plane via concentration and various rituals depending on the desired effect, anything from protecting the caster, attacking enemies, or simply providing information the dead knew in life or discovered in the underword. Undeath is a slightly more obvious category.
The death category includes but is not limited to spells that inflict horrible plagues, damaging important parts of an enemie's body like the heart or lungs for example, siphoning life from an enemy in order to gain something in return(maybe recuperate points on the shield's hit points), and anything from damaging souls to poisonous gas clouds, or swarms of ravenous insects. Necromancy typically involves any spell that deals directly with death, undeath, and sacrifice. Spells like drain life, or curses that cause damage over time. To counter this they have things like poisons, curses, hexes, etc to quickly dispatch enemies and provide fresh corpses.
Necromancers are typically not as strong without corpses to work with.
