You send necrotic energy into a humanoid skull. Your magic awakens the skull, turning it into an undead servant. The skull is infused with eldritch power, granting it the ability to cast spells. It becomes a flameskull (the GM has the creature's game statistics). It's proficiency bonus equals your bonus.
On each of your turns, you can use a bonus action to mentally command the flameskull you created with this spell. The creature must be within 60 ft. of you. You decide what action the creature will take and where it will move during its next turn, or you can issue a general command, such as to guard a particular chamber or corridor. If you issue no commands, the creature only defends itself against hostile creatures. Once given an order, the creature continues to follow it until its task is complete.
The creature is under your control for 24 hours, after which it stops obeying any command you've given it. To maintain control of the creature for another 24 hours, you must cast this spell on the creature again before the current 24-hour period ends. This use of the spell reasserts your control over up to two creatures you have animated with this spell, rather than animating a new one.
Even after the flameskull stops obeying your commands, it still obeys your general commands, though you cannot direct it to take specific actions or movement. You can order it to guard a particular area, but you can't control what spell it will cast or where it moves on its turn.
At Higher Levels. When you cast this spell using a 6th-level spell slot or higher, the flameskull's hit point maximum increases by 10 for each spell slot level above 5th. Additionally, the damage of its Fire Ray attack increases by 1d6 for each spell slot level above 5th.
* - (a humanoid skull, an opal worth at least 250 gp)
I know i'm late but this is quite good. :)
Thanks. I probably should've specified that the material components for the spell are consumed, so players don't create an army of Flameskulls with time to guard an area or follow them.