Did anyone actually thought this was a serious thread? It's one of these "I found old bone on the bottom of the lake in Elwynn Forest and that's an easter egg / reference to whatever"
Yeah, it's just typical voice emote bosses do when they cast abilities (for people who don't use dbm) and also the fact earthquakes cause tsunami ("crashing waves").
I need to remind myself next time Illysanna yells "you shall not escape" it's not just a reminder to use my active mitigation it's a reminder of inevitability of Queen Azshara expansion coming we cannot escape from.