Originally Posted by
Thage
Let's extrapolate from existing data, shall we?
Point one: Warlocks can form shields or enhance their fortitude with magic.
Counterpoint: This is true. However, these spells are limited in what they're capable of absorbing, it's not like a paladin's Divine Shield where all incoming blows are completely averted, or like even a priest's Shield spells where all damage is taken until the shield's magic is exhausted. It just makes them a bit sturdier. This is not enough to counter 4,000 rounds per minute from one 30mm minigun, to say nothing else of humanity's numerous other forms of heavy ordinance--the 30mm barely qualifies as medium ordinance.
Point two: Earth wouldn't nuke Draenor.
Counterpoint: Why the fuck not? The Dark Portal can be collapsed and destroyed from our end. Failing that, we can do what was done in Warcraft II: Beyond the Dark Portal, send a few heavily-armed battalions and air/artillery support, and close it from their side. Suicide missions are not unknown concepts to the military if the need is great enough. If the Dark Portal can be destroyed, there is literally nothing stopping Earth's militaries from running a missile train on Draenor culminating in a thermonuclear bukakke the likes of which would make Argus look like small potatoes, because with no Dark Portal there is no risk of fallout seeping through the portal into Earth.
Point three: Orcs are hardy.
Counterpoint: They are, but they're not 4,000 armor-piercing bullets per minute hardy, never mind sustained artillery fire, thermobaric explosives set off in their midst, or sustained drone strikes and ICBM launches. Explosives have been repeatedly shown to be quite effective against orcs in Warcraft alone, and the ordinance modern humanity is capable of makes the biggest Iron Star look like a kid's sparkler. They're definitely not hardy enough to survive charging a firing line that consists of dozens if not hundreds of rifles and mounted miniguns cracking off hundreds if not thousands of rounds in the span of a second, so the orcish infantry can close in to be of any threat.
edit: Again, if orcs in Warcraft lore can't shrug off bullets from Azerothian firearms, and warlocks can't make themselves immune to the same, there is no situation where the Horde has any hope of winning in an invasion against modern-day Earth, even if we give them the full breadth of the Old Horde's magical capabilities (which were warlocks, full stop, as orcs had no mages and the elements had cut them off) and even if we're super duper generous and give them Iron Horde technology. A modern machine gun can cut a man in half after a few seconds of sustained fire. Fucking hell, a .50 rifle leaves an exit wound the size of a basketball. Orcs are tough but they're not the Hulk, bullets don't bounce off them and even if Azeroth's chump bitch guns couldn't pierce them, modern military hardware is more than capable of doing the job.