>>516875898People of Azeroth get sick of everything going wrong and thus take up the elements and start a Not Twilight Hammer cult to dismantle everything and return to purity.
This results in a chain of events that breaks out 4 Dragons and the Dracthyr.
Purple Dragon is first freed and dies freeing other three.
Stone Dragon orders Fire and Ice Dragon to bully the morties while he goes on a side quest to get the Dark Heart, then team up with the Infinites to get the Dark Heart powered for Xal'atath
During this event the Tyrsguard begin rebuilding Tyr for the Aspects and go on a time-travel adventure with the help of Bronze Dragons and some infinite dragons. Tyr is recovered and is now a semi-active character in the story
Fire Dragon skinny dips in Shadowflame and starts going insane, while Stone Dragon leaves the expansion succeeding in his goals and ice Dragon gets second thoughts deciding to join team good guy.
Expansion ends with Fire Dragon seeking to enter the Emerald Dream backed by the Firelord Smolderon to destroy the new world tree growing from a seed the Night Elves got from the Winter Queen in SL.
Smolderon is betrayed by Fire Dragon, then Fire Dragon dies at the end of the raid and the new leaders of Dragon Society Alexstraza, Nozdormu, Kalec, Ebyssian, Merithra and the Ice Dragon Vyranoth get empowered by the world tree as it blooms into Azeroth.
Gilneas then is also recovered in a joint operation between the Forsaken and Gilneans back from the Scarlets, in which Genn then passes the throne to his daughter Tess, electing to continue his service to the Alliance in Stormwind instead while Tess leads their people.
That's every major thing leading up to the Harbringer questline.
