Render Silent and Abrupt Decay
Your opponent will be unable to cast spells for the remainder of the turn.

The ruling on gather for Render Silent confirms this:

http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=369022


  A spell that “can’t be countered” is a legal target for Render Silent.
  The spell won’t be countered when Render Silent resolves, but that
  spell’s controller won’t be able to cast spells for the rest of the
  turn.