This may be known to some wiki editors, but I thought I'd give a reminder, in case it isn't widely known...
Spoilerblur
If you use the class="spoilerblur", like for <span class="spoilerblur">Something you think is a spoiler...</span>, it will only blur for desktop browser wiki users. The code for this is ignored on the mobile skin, so it has no effect there.
Spoilerblock
The {{spoilerblock}} template will work on mobile, because the collapse code works there. So, if you really want something to be hidden, use {{spoilerblock|Something you think is a spoiler, but you really want it to be hidden.}}.