Bind Undead Dragon

This spell is among the most powerful of necromancy spells, as it raises a massive undead dragon to do your bidding, and binds it to you permanently. Choose a pile of bones or a corpse of a dragon that you can see within range. Your spell imbues the target with pure necromantic energy at the start of its casting, causing it to rise as a massive undead dragon (dracolich stat block) that is not controlled by anyone’s will, that is until the end of the casting, when it submits to the caster’s will. In the time between when it is raised and when control is gained over it, it must remain within the spell’s range, and the caster must maintain concentration as though they are concentrating on a spell. If concentration is broken before the spell has finished its casting, then it remains animated until killed and cannot be attempted to be bound again. If the dragon leaves the range of the spell before it has finished casting, then it turns to ash and cannot be resurrected again, and it is aware of this when it is raised. If the undead dragon is killed before the spell has finished its casting, then its corpse afterwards is immune to the spell for the following 24 hours, after which the spell can be reattempted upon it. You may only have one undead dragon bound to your will at a time.

On each of your turns, you can use a bonus action to mentally command the bound dragon if it is within 300 feet of you. You decide what action the dragon 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 dragon only defends itself against hostile creatures. Once given an order, the dragon continues to follow it until its task is complete.

If the dragon is outside of the 300 foot range, or has been killed, then you can use an action to summon it at an empty space that you can see within 300 feet of you. If you reach 0 hit points then the dragon is unbound from your will and cannot be bound again after that. If you die then the dragon turns to ash and cannot be summoned again.