Well if you look at historical legend, the quintessential necromancy spell is actually Speak to Dead. That said, here's necromancy from a project I've more or less abandoned, but which I feel does this well. The dots listed could be considered equivalent to spell levels.
Raise Corpses (•)
You lose all your mana. For every 5 mana lost this way, a corpse is raised into a zombie. It has the same physical abilities as it had before death, but is now mindless and strives only to destroy life. These undead are not loyal to you.
Prerequisite: Raise Corpse
You start a necrostorm. You lose all your mana, as does every mage caught within the perimeter of the storm. For every 5 mana lost this way, a corpse is raised into a zombie. It has the same physical abilities as it had before death, but is now mindless and strives only to destroy life. These undead are not loyal to you. The storm has a radius equal to the mana you lost in its creation in yards or meters. The storm raises only corpses in its area, and if it withdraws mana in excess of what would be required to raise all the corpses in its area, it persists. It loses one mana per hour while persisting in this manner. It is subject to being moved by high-atmosphere winds like any other storm.
Control Undead (•••••)
You control a single undead being. It no longer attempts to kill you, and you may direct it to kill specific others. Directing it to do anything other than kill has no effect.
Direct Necrostorm (••••• ••)
You have some control over the drifting of necromantic energy.
Target necrostorm drifts a number of yards equal to your channeling roll in the direction of your choice.
Lichdom (••••• •••••)
Cost: all mana, 13 innocent lives
By painfully killing thirteen innocents (usually babies) and binding their souls together with your mana, you create a phylactery, which houses your soul. If the phylactery is destroyed, your soul returns to your body. If your body is destroyed, you may recreate your body at the location of your phylactery. Your body can be created with a single hit point on the first day, and after that it regains 1d6 hit points until you choose to begin using your body once more, at which point it regains health as normal. Your new body has 0 mana when you begin using it, even if you had mana remaining when you were destroyed.
Note that control is much more difficult than creation. This was intentional to justify necromancy being inherently evil and not overpowered, as well as to make it a credible threat in the setting but still allow it as an option.