I think the colour on the background is alcohol ink, although it could be Copic markers, or refills… I have a vague recollection of getting a few drips of whichever on a piece of kitchen roll, quite liking the effect, and then deliberately adding a few more. It was quite a while ago, and it has been sitting in my odds and ends box ever since.
The crackle vase is much easier to place: that was a spare I made when I was creating this card. Crackle paste takes an age to dry thoroughly so I made a couple with varying thicknesses of paste in the hope that at least one would be usable.
Once everything was glued down and dry, I simply doodled a few flowers to finish it off.