Disguise undead

Disguise undead was an arcane spell that crossed multiple schools of magic including alteration, illusion, and necromancy. It altered the appearance of one or more undead creatures so they could pass for live, healthy creatures. A less effective but easier to learn illusion-only spell by the same name was later developed.

Effects
The number of undead creatures that could be affected by the earlier versions of this spell was equal to the level of the spellcaster. Each target grew flesh, organs, hair, and skin to resemble what they looked like when alive and healthy, although if deformed in life then the disguise included those deformities. The flesh looked and felt as expected for the type of creature, although it did not bleed, sweat, or smell. No abilities were granted to a target. If it could not speak while undead, then this spell did not grant the ability of speech, etc. Abilities that relied on smell or appearance, such as the nausea-inducing odor of a ghast or a fear-inducing visage, were negated by this spell. The spell took a full ten minutes to cast and lasted ten minutes per level of the caster. Also, all targets had to be within 10 yd (9.1 m) per level of the caster.

The oldest version of disguise undead was very powerful, combining alteration, illusion, and necromancy in a way that prevented detect undead (but also attempts to detect life) and turning for the duration of the spell. Even trying to divine the alignment of a disguised undead returned nothing or complete neutrality. The only drawback was many additional material components.

When wizards began to specialize in one particular school of magic, this spell ironically became difficult to impossible for necromancers and illusionists to learn because they were in a school diametrically opposed to the other specialty required to cast this spell. The result was that the later version of disguise undead did not prevent detect undead or alignment detection, and clerics and paladins could attempt to turn disguised undead once they realized the nature of what they were facing.

As researchers continued to make this spell simpler, a completely illusionary version was developed that was very similar to disguise self except it worked on one undead creature with a body to carry the illusion. The creature could be made to look like anything as long as the basic form of its body was unchanged (i.e., humanoids had to remain humanoid, quadrupeds had to remain four-legged, etc.) and the height remained within 1 ft (30 cm) of the original height. Fat or slim, ugly or beautiful, subtle or gross, the illusion could be anything the caster could imagine within the limitations of the spell. The smell, sound, and tactile feel of the body were not altered by this spell, giving a viewer an opportunity to disbelieve the illusion when one of the other senses detected something that the eyes did not corroborate. Note that disguised weapons still delivered the usual damage regardless of what they looked like. This spell was very quick to cast compared to its earlier versions, and yet still lasted ten minutes per level of the caster.

Components
All versions of this spell required verbal and somatic components. Material components for the earliest version were a drop of the caster's blood, a pinch of dust, a smudge of ashes, a bit of flesh, a sliver of bone, a human hair, and the cocoon of an insect. The newer version required only the insect cocoon. The illusion-based version specifically required the cocoon of a death's head moth and the caster had to touch the undead creature being glamored.

History
This spell was published in "Volo's Guide to All Things Magical" and became generally known to the magical community.