Forum:Royal Decree query

So I am well aware that you can dust tornado a royal decree after activation as well has a seven tools, but what if your opponent just so happened to dust your royal decree and you activate it; will it still be destroyed or is dust negated?

Example:

1 face down trap/magic on each players field. 1 person has dust and the other has royal decree. He/she activates dust to destroy my face down royal decree, but i chain to activate it. What happens then? wouldn't royal decree stay since it is the last part of the chain that was activated?

-Greekxican