Why Sargeras need a portal to Azeroth?

[Drfireburns]

Party Pooper.

It's because all Evil Villains need to have an Overly Complicated Plan to give the heroes a Chance To Foil It. Not even Sargeras is above the Dr. Claw Law.

Next time, Azeroth! Next tiiiiiiiiiiiiiime!

That is by far the best thing I've read/seen/heard all day. Thank you for making my day. I read that in Dr. Claw's voice btw.

[Snowraven]

They summoned him to Azeroth because he became too lazy, but he was so fat he barely could fit his head through the portal.

No, but really, he likes pain and suffering, and he sees it plenty. Plus, I belive he needed the most powerful of his minions to summon him. Now Archimode is dead, and he was one.
So he's probably travelling now. But we don't know how much it takes and in the meantime he still has other civilizations to conquer.

[Belimawr]

to be honest we havve never seen a true old god, we have only seen what they could project out of their personal prisons, so by the very fact they can project outside of the Titan prisons you would assume that they would be really powerful if they some how broke out entirely.

but then didn't they also say before if a old god was killed it would cause massive destruction to the world (the reason they got locked up in the first place instead of just destroyed)

but it took the entire titan group to imprison them, so chances are if one got free it could take on if not kill a titan, so far we have only fought projections of their power and never the true thing so they could be verry different.

[Ethenil]

Seeing as how Sargeras, Archimonde, and Kil'jaeden ALL had to be summoned from somewhere with powerful magics (WoE, Dalaran, Sunwell), I think that maybe Azeroth has some kind of "atmosphere" that protects it from outside invasion.

An atmosphere that the Cataclysm might have shattered....

[Grocalis]

Someone brought up to me that Sargeras has technically been on Azeroth before, as he was defeated by Aegwynn and later possessed Medivh. I figured I would explain how this occurs based on the novels. It was shown in detail during The Last Guardian.

During the age when Aegwynn was the Guardian of Tirisfal, she had learned that a small army of demons had somehow entered Azeroth, and had started hunting dragons in Northrend. She travels up to Northrend and starts combat with the entire force, but they open a quick portal from which they start bringing in more demons. Aegwynn, not wanting to get overwhelmed, focuses her magic on the portal itself, hoping to use the portal as a weapon versus the demons. She does so, forcing the portal to flare with power and then quickly collapse in a massive explosion, which obliterates all the demons. As she pats herself on the back for a job well done, suddenly another presence appears, and his voice shakes the mountains. Sargeras was on Azeroth.

While never outright said, two things are implied during these events in the novel. First, Sargeras had weakened himself to allow easier passage through the gate. He was not at full strength. Second, Aegwynn's gambit to empower the portal to make it detonate was all part of Sargeras' plan, as he waited for the time the portal was at it's most powerful from her magics to step through, just before the detonation. It was his weaker form combined with his arrogance that allowed him to be defeated, as behind her back Aegwynn was charging up a spell that turned the demon lords body to crystal, unleashing it just before Sargeras could make his killing blow. He infused part of his essence into her before the turn, thus allowing him to later possess Medivh.

As for how Sargeras got back to the Twisting Nether in time for him to be calling the shots again, we don't know, but some sources claimed that when Medivh was killed, the demon lords spirit was banished to the Abyss. It could be his spirit simply returned to a section of the Twisting Nether, a shell of it's former power, it took all these years for him to reform. We know by the time of WOTLK he has retaken control of the Burning Legion, so either he reclaimed his form, or he is still just a powerful spirit hoping to reclaim his body by the time of the next expansion.