I'm happy I understand both a VMC descent and a Visual approach. I understand their use and application and who is responsible for separation etc
By VMC descent, are you referring to own terrain clearance visually, or maintain own traffic seperation visually? If the former it is the pilot's responsibility to maintain a safe terrain clearance when below MSA. Used in situations where the requirements for a visual appraoch are not yet fulfilled, but expected to be.
If the latter, I don't know. Used to be an option here (NZ) but think it may have been withdrawn. I'd have to check MATS when at work next.