From Page 44 of the RRG, v1.4:

WARNING (#21) Should read: “Interrupt: When a hero would take any amount of damage, reduce that amount by 1.” (Removed “(defense)” and the Defense trait.)

This make this card infinitely better as it can be used to mitigate Indirect damage, prevent damage to other players in Hero form, and doesn't require you to (or cause) attacks to be redirected towards yourself.

Excellent change, and more people should be considering this card to see if it is appropriate for their decks

It also makes it much, much worse for Shadowcat, who otherwise could have used it as a 0-cost way of getting into Defense state without having to play Protection for Defiance. No, I'm not annoyed at finding that the oh-so-clever trick I thought I'd found was pre-emptively erratta'd. Why do you ask?