"you can use today" definitely needs an asterisk.
True, though you technically "can" use it today... but "should" you? probably not.
These features are nice, but you definitely shouldn't use them today because unfortunately most of us develop in a climate where legacy browser support is non-negotiable.
I am, however, very excited to develop 5 years from now.
It's a huge dealbreaker that Firefox doesn't support image masks. Which is a bummer: they're very useful, and they're used in such a way that they don't gracefully degrade when not supported.
Does anyone know of any good codepens or examples on the web or this kind of CSS stuff?
I'm calling it now: blend modes will be the next big web design trend, especially multiply and screen.