Q: The rules say you can play the Rainbow Dragon “anywhere”. Does that include on top of the Silver Dragon, like an Action card, to change it back to wild?

A: Technically, we never intended for Action cards to be played on top of the Silver Dragon, however, some people do choose to play that way.
See: In Seven Dragons, can we put the discard pile on top of the Silver Dragon to easily see what color it is?

Whichever way you choose to play, the Rainbow Dragon is a panel card and not an Action, and as such, can be played anywhere a panel card can be played – which does NOT include the discard pile, wherever you happen to be keeping it. Note that we do have a Shuffle Hands promo card which IS an Action that changes the Silver Dragon back to wild, and which is available in our webstore.