Class Changes and Flavour

Druids
Druids function differently in this world. Less associated with nature, and more associated with the Darkness itself. Deep Druids wild shape into various monsters from the dark, rather than animals, and control various elements of darkness. Most Deep Druids are mistaken for Ghouls, and a fair amount of ghouls are Druids in the first place.
Nature Druids are much rarer, but still exist. They most often found closer to civilisation, as those who venture out into the darkness in search of nature worship seldom find it.
Bards
Bards are important - music is one of the few things apart from light that - somehow - keeps the Dark away. Not as effective as light, but a song with feeling behind it will do in a pinch. Bards are often sought out as a vital member of an adventuring or travel party. Music and Darkness
Clerics
Clerics are considered the only magic class to create real sunlight, and thus are revered in a lot of circles.