Branimir's Legion of the Dead

Your place a black gem in the mouth of a wight's head and pour your blood over its scalp and whisper an incantation that launches a field of negative energy in a 300-foot cone in front of you. Every creature in front of the cone must make a constitution saving throw, plants and other organic items fail this save automatically while undead automatically succeed. On a failed save, all creatures take 10d10 necrotic damage. On a success, creatures only take half damage.

When a creature dies to the necrotic damage, their bodies become suffused with the Negative energy plane and they become a wight or a deathlock wight if the creature knew how to cast one spell. They are permanently under your control. If a creature that was undead dies to this spell, they are brought back to undeath with half their hit points and are now under your control. This ability does not work on revenants. If a creature that was not humanoid dies to this spell they become a zombie variant of themselves and develop the undead fortitude trait, they are unable to cast spells. The only limit to how many undead you may have under your control is that they must be within the cone. If the cone of negative energy hits a corpse it also becomes a wight unless it is missing limbs, in which case it becomes a zombie.

If there are no corpses to cast the spell on and it is cast in a cone with no creatures to infuse with negative energy, you may pull any type of incorporeal spirits from the negative energy plane or the Shadowfel but not more than 300 Hit points worth of them. The Creatures can only be of CR 5 or lower and you cannot have more than 3 of the same type of undead spirit. For example: 3 banshee, 1 wraith, 2 poltergeist equal out to 285 Hit Points worth of creatures. This is just one combination and any combination of spirits under CR 5 is capable of being utilized. 

All undead under the effects of this spell are under your control until you die, after which they will begin to act as their normal selves which may include attacking any living thing nearby. You must be near the undead in order to issue commands unless you utilize magic that allows you to communicate with them by other means. If no commands are issued, they will guard the location they were summoned and fight to defend themselves. Any intelligent undead would not leave themselves in a situation they would be likely to perish in, unless a command was given. If the caster of this spell is ever making death saving throws, the undead under their control will fight to protect and revive their master by any means necessary. 

This spell can only be cast once every 30 days and the previous undead are not destroyed when you cast it again, they are added to the legion.