Ilyykur's mantle

Ilyykur's mantle was an arcane abjuration spell that gave the caster some protection against various types of magical attacks.

Effects
This spell gave the caster a protective aura that covered the body in a soft, form-fitting glow. Ilyykur's mantle was particularly good at protecting the caster from enchantment/charm spells, but also granted a minimal boost to protection from all other types of spells. One additional feature was that all damage from electrical attacks, such as lightning bolt or shocking grasp, was reduced by half.

If the caster had a small familiar with which it maintained contact, then the familiar was afforded the same magical protection.

The spell's duration was a matter of minutes, depending on the power and experience of the caster.

Components
In addition to verbal and somatic components, this spell required a natural, uncut, unpolished gem of any value. The later version of this spell specifically required the use of an uncut diamond.

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