Hello.

There are some event cards with no printed House affiliation (like every event), but with a "House X only" restriction.

Are those event cards considered neutral for gaming purpose?

For istance, with Empty the Vaults plot, from Five Kings:

"At the beginning of the marshalling phase, reveal your hand. Discard all cards in your hand that do not have your House affiliation"

Thank you

Basic definition of event cards: "Though many events’ text abilities refer to a specific House, events are always considered neutral."

No event will ever have your House affiliation, no matter what the card text may say.