If this mask is famous, it is also because we wondered a lot about the contributions of Negro art to Picasso's painting.

In central Pende, the Mbangu dance evoked the epileptic and served in some way to individuals to reconsider their attitude to their own misfortunes but also to the disease of others.

His song was:
Do not make fun of your neighbor
Do not laugh at your brother
Sorcerers have bewitched him
(source: Z.S Strother Inventing Masks)
Driven by wizards; he was, but he seems to have been a hunter too. By his dance, he evoked his desire to pursue these wizards and to harm those who had caused him harm ...
Combat against the disease, opposition of white and black colors in this deformed face.

This African mask represents the disease. He is part of Mbuya and is Mbangu type. It has an obvious deformation of the facies and the color scheme also represents the disease.
These masks appear during festivities intended to make the spectator aware of the impacts of the disease and in particular of the epilepsy that twists the features.
The pellet on the top of the mask probably illustrates the stigma of smallpox.