They could have sided with Malygos for all sorts of reasons. Slaves would be one big one. Another could be infiltration- trying to stop Malygos's machinations from the inside. Others, self-preservation. Side with the Spellweaver, possibly keep your magic when the Nexus War is through.
No doubt some of them think Malygos is right, too. A few members of the Kirin Tor think Malygos has the right idea, but his approach is disastrous and extreme, so they don't side with him. They think his actions are extreme, but maybe others don't think so at all.
In the Oculus, you fight Mage-Lord Urom. His words make it pretty clear that he thinks Malygos is right, and is doing what he's doing for the good of Azeroth. When you first meet him, he says, "Malygos is saving the world from itself!" When you take him out, his dying words are, "Everything I've done... has been for Azeroth..." He thought he was doing the right thing.
There are likely plenty of people that see things the same way as Malygos. Magic has to be brought under control. Magic has ruined Azeroth before, and it could do so again. From their point of view, you might even say that the Kirin Tor getting in the way has forced Malygos to do so many bad things. Would Keristrasza have been enslaved (and later killed) if we didn't kill Malygos's consort first? Probably not. Would the Blues have killed so many if we laid down arms? Nope.
Of course, it probably would have left us open to attack by outside forces like the Burning Legion... but maybe not. Who's to say Malygos wouldn't have helped us, in the end?
Personally, I'm on Dalaran's side, and I don't want to look like a Malygos apologist or anything. Just sayin', it's easy to see how people would side with the Aspect of Magic over the Kirin Tor.
I'm curious, Why do and Horde and Alliance want to kill Sartharion in the Obsidian Sanctum? The boss does not appear to be doing anything particularly evil. Are we just killing him because of Nefarion and Onyxia?
I answered this over in The Queue, but it fits here pretty well, so I'll plug it again. It's a follow-up to the events in Night of the Dragon, yet another poorly written and poorly timed book. It's written like it's supposed to set up some of the events of Wrath, but was actually released after it.
Basically, Sartharion is protecting Twilight Dragon eggs. The Twilights are another hybrid creation of the Black Dragonflight. It's an attempt to recreate and bolster the flight, like Nefarian's Chromatic Dragons that we dealt with in Blackwing Lair. If you've done the quests on Netherwing Ledge in Shadowmoon Valley, you might remember meeting Lady Sinestra, one of Deathwing's lackies.
She showed up on the Ledge and asked for Netherwing Eggs from the Dragonmaw. This is a direct continuation of that. The Twilight Drakes are a Netherwing/Black Dragon hybrid, and they feed on magic, including magic of other dragons. They're bad juju. Sartharion is protecting a crapton of Twilight eggs beneath Wyrmrest in the Obsidian Sanctum, and we're dealing with them before they all hatch and grow into an army of magic sucking drakes/dragons.
They give no indication of this in-game, which is a real pain. They could at least give Krasus some flavor text about it, you know? But that's why we go in there. To deal with the Twilights. Sartharion is given the job of protecting those eggs, so we have to go through him.
I've been wondering, how is it that we are allowed to kill Malygos? Isn't killing an aspect kind of messy lore-wise (especially an aspect of magic)?
Nope, not really. It's a common misconception that an Aspect's death would have massive widespread ramifications for Azeroth, but that's never been proven or given much weight. Mortals had no idea what was going to happen, but that doesn't necessarily mean something would happen.
The Titans empowered the Aspects to keep an eye on Azeroth. To watch over it, and guard it. Azeroth certainly existed before the Aspects. Think of them more as Guardians, rather than Keepers. Malygos watches over the ebb and flow of magic. He doesn't control it, he just makes sure it's going alright. He's there to make sure it doesn't get out of control. He isn't the source of magic, he's just the guy that's supposed to oversee it all.
Likewise, Nozdormu isn't Time itself. He's supposed to be the guardian of Time. The stuff we see going on in the Caverns of Time is specifically why he exists. He's there to stop things like the Infinite Dragonflight from cocking it all up.
The death of Malygos won't make magic explode the world or anything, but it does put the responsibility of watching over it much more heavily into the hands of other people. There's no dedicated overseer of magic now. Mortals will need to take things into their own hands, and other Blue Dragons will need to step up.
The same with Nozdormu. If he died, the most powerful defender of Time would be gone. The timestream would be made more vulnerable, but it wouldn't stop moving. Other people would need to step up, and mortals would probably need to take a more active role in the Caverns of Time than we are right now (though we're definitely chipping in a whole lot already). And Nozdormu will be gone one day. The Titans specifically showed him when he'll die, so he doesn't get too cocky about his power over Time. He's not above death. Even Nozdormu will die one day, and that right there is pretty good evidence against world-wide ramifications of an Aspect's death.
Maybe the Aspects are just starting to outlive their usefulness. Maybe mortals have reached the point where they can fight for themselves and don't need massive dragon overseers controlling their actions. Who knows? If we can kill Malygos, we're probably capable of watching over magic on our own.
Or maybe we're not, and the next expansion is the downfall of Azeroth. Who knows!
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