This inaugural edition will take a look at the most unlikely figure I could come up with for the main antagonist of an entire expansion. So here we go, ladies and gentlemen, with my rampantly untrue, completely made up, based on nothing but my own ideas speculation for what we could see in an expansion around the idea that the main bad guy is none other than the Prophet Velen.
Yes, that Prophet Velen.
Velen is over twenty five thousand years old, and he's spent much of that time in a pitched battle of wits with his old friend Kil'Jaeden. After having settled on Draenor and daring to believe it was finally safe to relax, he had any illusions still remaining to him shattered by the orcish Horde, and saw many of his people massacred by them. Taking what few refugees he could into the Zangarmarsh, in time he staged a recapture of one of Tempest Keep's satellite structures and in that craft, the Exodar, he and his people ended up stranded on Azeroth. Velen is keenly aware of the threat the Legion still poses, so keenly that threats like the Lich King and Deathwing almost passed unnoticed by him. Like Wrathion, Velen wants to see a united Azeroth, so much so that he has visions of it happening. But Velen knows that the things he sees can happen. So, following the destructive conflict between the Alliance and the Horde, imagine if Velen decides its time to make things start going towards the desired outcome.
Velen has so much more life experience than just about anyone on the face of Azeroth outside of a dragon aspect or a Titan construct that he's capable of a great deal more subtlety than, say, a two year old dragon whelp. He understands the truth of balance in a way not even a pandaren elder could match. He has no desire to see the Horde destroyed - see how he intervened to save the blood elves by reigniting their Sunwell. It benefits Velen's plans to keep both factions around and pointed in the direction he wants them to go. So imagine Velen begins his plans by influencing the Alliance to mount an expedition to Argus, and lets the Horde know all about it, ensuring that they'll mount one themselves. Furthermore, he arranges for this expedition to stumble upon Burning Legion forces, deliberately pointing their interest back on Azeroth again. He manages to connect up with a group of eredar clinging to their old ways of existence, knowing that they view him and his followers with disdain for their constant retreat in the face of the Legion, indeed counting on that disdain to push them to ally with the Horde forces. He works to steadily embroil both factions in conflict with the Legion, drawing their forces to Azeroth, and even makes a target of himself so that the dreadlords make a move against him (exposing their latest plans to influence the mortals of Azeroth in the process) knowing that in so doing they'll commit Azeroth even more fully to the conflict.
The middle of the expansion would be a full-fledged Legion invasion into Azeroth, one that has to be faced and stopped before any mortal heroes can even think about taking the war back out into the greater cosmos. By the end of the expansion, both the Alliance and Horde have allies with transdimensional travel, have balked the Legion on Azeroth (not without great cost, as several of the greatest heroes of the Alliance and Horde perish in the fighting, and some of her cities are heavily damaged or destroyed) and are taking steps to try and liberate Argus from the Legion presence. Raids on Xoroth are followed by a full-scale push into the Nathrezim fortress in the Twisting Nether, because the heroes of Azeroth find that only in the Nether can a dreadlord be truly, finally destroyed. The end raid of the expansion is a full-scale war on the Nathrezim homeworld, and the final deaths of the dreadlords. And then, and only then, do the heroes find out that the entire war, from beginning to end, was stage managed and set up by Velen. All the people who died on Argus, on Azeroth, and in the final invasion of a hellish world ruled by the Legion's most foul deceivers are dead because Velen set it all in motion.
And that's it. There's no fight - Velen has left no evidence. No one but the players even know what he did, and they only know because he wants them to know. They can tell others, but that will just serve Velen's ultimate goal of keeping the Alliance and Horde separate while keeping them pointed at the Legion - after the destruction of the Nathrezim, the Legion as a whole is now squarely aimed directly at Azeroth, and any attempt to divert focus to take Velen down would just leave Azeroth without his valuable information when the hammer falls. Velen lets the players know what he did entirely to foster their sense of suspicion, because against the Legion, even paranoia is a weapon. In order to forge the future he foresees, Velen will do anything. Even risk his own death.
Next up will be Anne, and her take on an Alexstrasza themed expansion.