Really? We've done it twice—Yss from the brink of death, and Zathir. And the Old Gods are being stuffed, and we're due to help the Fourteen the same way eventually.
These big sacrifices are something we work towards for months. It's very much part of our legend. When people look to Sorcerer's Deep, blood sacrifice definitely pops into their head.
I feel like this aught to at least count towards the next Mythic Rank.
That is fair, there is some history there. Let's call it half a mythic tier for simplicity, a deed that does not quite harmonize perfectly, but is important enough for a significant boost.