do you have the desert unlocked?
if yes: no.1: find the dull blue imp and get captured by her
no.2: she'll make you drink something (it'll appear on your hotbar?)
no.3: aim the given ability downwards you'll get a temporary dick
(to get it permanently you have to repeat the previously mentioned steps about three times?)
if no: defeat the tar wolf go through the portal to the parish and at the far end you'll see the portal to the desert and refer to the steps above
edit: sorry for the infodump