How to duplicate Spoiler or create a NSFW bbCode/Block?

[Shadow Wolf]

I am trying to create a NSFW button that functions similar to Spoiler button. Previously with customBB Code this was easier but now that isn't used, it is a bit more complex. I was hoping to simply duplicate how it is done with Spoiler, then just change the CSS to match what I want it to do. It doesn't appear that I can even duplicate the Spoiler piece. 

I'm going into the Admin Control Panel, Customization -> Editor -> Toolbars -> Add Button. Selecting Custom, I type in the name, choose a .png icon. I started with Block, since I think that is what I want but I did try Inline and Single Line Block which is also not working. I don't believe we are using an option but we are using {content} to post what I want within the tags. 

I would settle for being able to edit the heading for the spoiler piece. CKEditor has a Spoiler option to edit contents. I did try that but it doesn't appear to be working. It lets me edit and everything looks fine during editing, until I save my post and then all the CSS/HTML piece for it gets stripped.

If I can duplicate Spoiler so I essentially have Spoiler and Spoiler-NSFW then that would be fine. Or add an NSFW tag. Or add something to make Spoiler header editable. It used to be you could do spoiler=Text and that would put that as the title but since it is now CKEditor that doesn't appear to work that way anymore.