25% Darkness Requirements
Nemesis Shield
Shadow Cloak
Head of Raydius Dragon (or some other item that offers -10 dark)

17% Darkness Requirements
Shadow Bones
Shadow Cloak
Head of Raydius Dragon (or some other item that offers -10 dark)

Equip all and get attacked by a darkness monster so your Shadow Bones shields normal -13% darkness can go down to -23% darkness to give your darkness defense an over all 17%

Hope you find this useful.