just another suggestion, my 2ct, since the mask is quite thin and quite close to M's face.

The mask might cast shadows onto M's face, and the Shadow Min Bias of the light lifts the shadows a bit from a face (to prevent artifacts from displacement mapping). But it might lift too much and warp the shadow to the front side of the mask. So, reducing the SMB for the light(s) - and perhaps turning off shadow casting for the mask - might be of some help as well.

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Usually I'm wrong. But to be effective and efficient, I don't need to be correct or accurate.

visit www.aRtBeeWeb.nl (works) or Missing Manuals (tutorials & reviews) - both need an update though