Quest Text is not a game mechanic. Its descriptive. If Blizzard wants you to go an NPC that isn't near you, and doesn't want said NPC to "talk" to you from long range, then they have no issues (and never have) just having you get the next quest stage as "Alextrasza motions you over" or "You should go see if you can figure out what the dragons are doing here and talk to Alextrasza".
But they had her clearly imparting words to you, when that wasn't necessary, and in other situations like that, they simply provide you with a generic reason to go over and talk to the NPC in question; in this case, she's imparting deliberate words/information to you. While nowhere near you.
You're too focused on being a massive pedantic jackhole that you are deliberately ignoring the part where the person you're arguing against already said it doesnt have to literally be psychic telepathy. It could be literally anything. Magic, innate ability to vocalize without moving their mouths, psychic powers, whatever. You're so hung up on the super-specific 'telepathy' angle that its almost worrying.Not it absolutely isn't. And Kralljin pointed out exactly why it isn't telepathy. The fact that you are treating quest text that doesn't even mention telepathy as if it actually IS telepathy is asinine.
Some Dragons (or at the very least, Alextrasza) can make people hear them from a distance. We know this because its literally happened.
Arguing otherwise just makes you look insane.
Wether them not moving their mouths in this cinematic is just Blizzard's laziness, or not, is immaterial. Because we've already seen it happen, in-game, we know its possible.
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The difference is that the Lich Kings actual plan was to let you get powerful so that when he insta-killed you all at the end he could raise you all to be extremely powerful Scourge Lieutenants to lead his armies. Like, he WANTED you to get powerful. If not for Deus Ex Tirion breaking Frostmourne, Arthas' plan worked. He won. He killed us all and was going to complete his plan until Tirion's impossibe-to-predict escape from his ice prison shattered Frostmourne.
It does not appear that this rando hitherto unknown Mega Dragon has that plan in mind.
Its just being a tropey villain. Which, i mean, isn't necessarily bad. Implementation is key. So far... not impressed, and this appears to be bad-tropey.
And that dungeon was Zul'Drak. Zul'Gurub was in Vanilla, and then re-used in Cataclysm, and is in Stranglethorn Vale. Zul'Drak is a zone and 5-man dungeon in Northrend.