Sadly this isn't an actual card. It's fan art by oh-the-humanatee.
Rainbow Blight is also the name of the front woman of Hate In The Box,
a creepy, cool, candy-coated horror rock band from NYC.
As for Blight's inspiration, Rainbow Brite, I just bought a doll of her.
Which was actually advertised for by Heather O'Rourke (Carol Anne)!