After reading the recent comments, I had a few things I wanted to say.
I thought about the Arthas invasion storyline for a long time.
First, both the Sunwell and the World Tree were products of a vial of water from the Well of Eternity, and both were things Archimonde and Kil'jaeden wanted. If Archimonde arrived and discovered another Sunwell in the north of the continent-and don't say the Sunwell had already been corrupted by then; Archimonde wouldn't have feared the Lich King's little plagues-then he would have gone to Quel'Thalas instead of heading to Mount Hyjal in Kalimdor.
After all, Kil'jaeden coveted the Sunwell's energy too, so why wouldn't Archimonde? If Archimonde attacked Quel'Thalas, it wouldn't just have suffered devastating losses; its people would have been wiped out outright. Archimonde's power wasn't something a demigod could compare to. Even Malorne, the strongest demigod back then, had his neck snapped by Archimonde, and the other demigods were even less worth mentioning before him. If Archimonde personally attacked Quel'Thalas, how was I supposed to handle it? Bann'donor was like a sheet of blank paper before Archimonde. After stealing Karazhan's records, Dalaran built the floating Violet Citadel in the lake behind it. Although it was only a citadel, it protected Dalaran's mages and kept them from being wiped out. But what about Quel'Thalas? Was I supposed to let Archimonde exterminate the High Elves? There was a reason Kael'thas destroyed the corrupted Sunwell after returning to it.
Second, if I changed the story, kept the undead from appearing, and stopped Arthas from attacking, the scope of the changes would have been far from small. The Scourge had the Burning Legion's support behind the scenes, and the Burning Legion's main aim was to plunge the continent into chaos, then enter Azeroth and finish Sargeras's