The Master's Face

The Master's Face was an artifact known within the ancient Imaskar Empire. It was once thought to be one of the Imaskarcana.

History
An alliance of Imaskari archwizards known as the Cabal of Madness created a number of masks known as the Faces of Madness, each themed around a school of magic, over decades after striking a bargain with horrors from beyond their world. The Master's Face was one of them. Each of those major artifacts were created with a curse that only the creator knew how to avoid. Before they were able to implement their plans, however, the Mulan rebelled with the aid of their gods, ultimately destroying Imaskar as a nation. In the resulting tumult, the masks were scattered.

Appearance
The Master's Face was a bulky, terrible mask made of cast iron. It had humanoid features, thirteen short horns, and covered the wearer's entire face.

Powers
The Master's Face granted a continuous, overwhelming resistance to conjuration spells, and empowered the caster's own conjurations to defeat innate resistances against all spells. It also prevented summoned creatures from striking the wearer of the mask, unless they possessed the mettle to fight off the compulsion. Finally, they got the ability to cast, thrice a day, their choice of planar binding, gate, summon monster VI, summon swarm and mount.

However, every time the mask was put on, there was a chance of one in five that it would curse them so that any creatures they summoned or called became immediately hostile towards them. It took a remove curse, limited wish or something even stronger, cast with power at least rivaling the artifact's level in order to nullify said effect. The chance was cumulative.