its not good. Im not gonna be one of those people waving my arms freaking out because if your considering this it doesnt matter if its real or not you will put all your anxiety into something that doesn't exist. How people build up fears and such.but you don't need essentially an imaginary sex partner.At no point is it a good idea. You can not have sex with something that is in your mind. you are feeding kinetic energy into this pre-thought out thing and you will end up feeling like you are wearing body weights just to keep the anime girl dancing in your head. Its not worth it. you want to hold the mermaids hand go ahead make sure you can breath underwater. I imagine with a succubus gradually your life would just become more shiny until you can't see and that is probably a full blown demonic attack at that point. But without seeing anything its an invisible light that will burn out your emotional creative balance. Now if you are already succed in then you can do nofap for whatever is hard for you and a little beyond. Try to cheat on the anime make up or envision a new waifu that is a ninja fighting the other one. But just do this mentally do not fuck the waifu mentally. Use that to have her fight off the succubus. Use one daemon to stop the other. or simply pray. Its not christian clearly its not even really satanic even unless you have some kind of character made to be a succubus. I often wonder if that is what is going on with the snake anime mixtures. Sure its a sleek monstergirl in the anime drawing. You draw it yourself it looks like a pile of shit you are trying to invoke in a primal manner. Bad idea.