Originally Posted by
Mellrod
I'm pretty sure it didn't happen overnight, and it wasn't an easy task. Can't remember where, and correct me if i'm wrong but either in one of the War of the Thorns novels or somewhere else the scene took place in greater detail than the cinematics/warbringer short. I'm pretty sure it was mentioned that getting the tree to light took a very long time, that they used magical fire instead of normal fire (which goes without saying doesn't burn out as easily or follow the same physics.) Ontop of that iirc they had groups of shaman using the wind element to fan the flames and more fire-starting units mounted in the air. If nothing else, certain that Blizzard specified it was magical fire used by horde casters to light the tree. The rest is at least a headcanon for me.
What we see in Warbringers is pretty obviously a jump-cut. all you need to know is that it was burned, it's a narrative device. If they spent so much time showing us the burning in a brief 3-5 min short, it would ruin the storyboarding. Imagine if whenever someone has to get from point A, several hundred miles to point B, they showed every grueling hour of travel just so people wouldn't have to suspend some level of disbelief. Not very cinematic.
As for the Vindicaar, which is arguably the most powerful weapon in either faction's arsenal due to the sheer technological advantage, that thing is benched for obvious story writing reasons, but it already lost it's ability to rain down orbital bombardments when it spent the rest of it's power opening the way to Antorus, so Velen can't use it to just nuke Orgrimmar (nor do I think a semi-pacifist with golden morals like Velen even would do that). Don't think the Army of The Light would do it either.
When it comes to teleportation, the alliance side of the War of The Thorns characterized some of the limits to portals and teleportation better than the video game mechanics do. Teleportation typically only works on one, maybe two people at a time (save for mass teleportation, which I can only assume requires a very powerful mage like Khadgar or Jaina), and portals are hard to maintain, and can only transport a small handful of people, like a small squad of 3-5 people at best. When the fires started to burn Darnassus, they described how mages in the Stormwind wizard tower were sweating beads and beginning to collapse, exhausted as they stood in place trying to keep the way open for hours. Refugees could only enter the portal one at a time having to form single-file lines that probably looked like the lines outside of a soup kitchen. They needed people to stay behind on the other side and keep the masses from panicking, making sure everyone stays in line, and even then, with multiple mages supporting portals and people helping out, they still weren't able to save everybody before the fires reached Darnassus.
I think that alone speaks to the lore difficulty of portals. If you could transport entire armies through simple mage portals, I doubt the Orcish Horde or the Iron Horde would've needed a 10 story gateway constructed by hundreds of slaves, and powered by a constant flow sacrificial souls, to get their armies through to invade Azeroth.