Lady Amy wears tight PVC-jeans and treats her slave under her ass.
PVC is a properly sealing material, so the face under her will not be able to breath any little sip of oxygene without her permission.
First she sits foreward on his face crushing his nose slightly.
Then she moves around sits sideward, reverse and so on.
While reverse sitting she finds his nipples... a painful encounter!
Sitting on his throat, she clamps and squeezes his head, deforms his face.
To the end she spit on his worthless face.