The famous “year of the mammoth” quote wasn’t just about Tyrande:
Will the past promotional heroes and card backs be available again?
We are looking for ways to give players another chance to get the promotional heroes and card backs. For example, Tyrande Whisperwind was not available worldwide, so we’d like to give another chance for players to get her again. So, we have a good news - we should be ready to bring some of them back in the Year of the Mammoth.
https://www.invenglobal.com/articles/1165/qa-session-with-producer-yong-woo-about-the-past-present-and-future-of-hearthstone
So, as we bring this part of our journey to a close. It seems time to begin phase two. On that note, anyone interested in continuing this journey can head over to the official “Missing heroes and card backs, where oh where (year of the mammoth promise)” thread: