Vecna's Greater Animation

This spell creates an undead servant. Choose a pile of bones or a corpse of a humanoid, beast or monstrosity of huge size or smaller. Your spell imbues the target with a foul mimicry of life, raising it as an undead creature with its maximum hit points restored. The creature gains the undead fortitude feature and its intelligence score becomes 1. If the animated creature possessed any spellcasting ability, it loses it once it is animated. If the animated creature has any legendary, mythic or lair actions, it loses these once animated.

On each of your turns, you can use a bonus action to mentally command any creature you made with this spell if the creature is within 60 feet of you (if you control multiple creatures, you can command any or all of them at the same time, issuing the same command to each one). 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 a creature animated by this spell, rather than creating a new one.

At Higher Levels. When you cast this spell using a spell slot of 9th level, you may animate or reassert control over a creature of any creature type or of gargantuan size.