Orzhov Gatemaster

When Orzhov Gatemaster enters the battlefield,
you get {e}{e}{e}{e}.
Whenever a Gate card enters the battlefield under
your control, search your library for an angel card,
put it into your hand, then shuffle your library, if
you got an angel card this way, you can cast it for {e}{e} instead of it's normal casting cost.
{w}{b}, {t}: search your library for a Gate card, put
it onto the battlefield tapped then shuffle your
library.