There are seven secrets in this deck, but technically, you will have 11 because of the new twinspell, Desperate Measure. It is also important to remember that Secretkeeper doesn't respond to Desperate Measure, as it isn't a secret but a spell that casts secrets.
A new weapon Mysterious Blade is also included which synergizes very well with all the secrets in this deck. Finally, the legendary card Commander Rhyssa is also included, which triggers all of your secrets twice.
One of the better cards from the previous expansion, Bellringer Sentry, is here to support the archetype, as well as Subject 9.
But the best inclusion is Sunreaver Spy, a two-drop that becomes a 3/4 in case you control a secret. That is very powerful no matter when you play it.