Bringing Down the House

This achievement was added in 11.2, the patch after Liberation of Undermine. You will get this upon logging in if you're already renown 20.

A good addition, because there was definitely a lack of fanfare when people got max renown before!

Renown 20 unlocks:
High Roller title
Path of the Full House - Raid teleport tell (on a different cooldown to M+ portal spells).
Furious Flarendo mount purchased from Ando the Gat

if you are here because you are wondering if there is any other way to get this achievement except raid, unlucky for us, raid is the only way. 2 renown levels per week(one full clear of the raid) works on normal,heroic and mythic, i havent tried on LFR.