Attack of the B-Team Curses System (Witchery)

Since it doesn't say in the rules that we can't curse other people using Witchery, can we have a good system for allowing curses? I asked BenS the moderator and he said I should ask them first, but I could post on the forums to ask for a better system. So could we have a system for allowing curses where we don't have to ask for permission and make it like they don't know it's going to happen or just like how someone would curse someone normally by plainly throwing ingredients in and doing the curse?

 

Dangit. But can I do curses if they agree? And what if it's a non-harming curse? Like a curse of insanity only does illusions, no actual damage

 

Thank you!