Mordremoth had a Mouth, too, though; the Mouth of Mordremoth is what we kill in the Dragon's Stand metaevent. https://en-forum.guildwars2.com/discussion/comment/496222/#Comment_496222 Basically, us killing the Eyes and Mouth(s) of Zhaitan. This had weakened him physically, and not just in starvation; capturing the temples and cleansing the Artesian Waters would have also weakened him a bit, but not as much. There's no need to speculate this, even after this got brought up and linked to by Tyson. His weakness was reliance on specialized minions (he is the only Elder Dragon to have minions as specialized as the Eyes and Mouths of Zhaitan). Not minions in general, but his specialized ones - the minions that are directly (via magic) connected to him in a way the other minions are not. Because the Eyes and Mouths are directly connected to Zhaitan in a manner other minions aren't (Zhaitan knew what all his minions knew, and we know from the asura PS that all risen absorbed ambient magic in a region, as is the case for all dragon minions, but the Eyes and Mouth were more "real time" and much more effective in doing these two roles) killing him left him weakened. Then we deprived him of multiple powerful energy sources (the temples and Artesian Waters), and finally we struck him with lasers based off of Gorr's "reverse corruption" magitech and Kudu's study of the Elder Dragon energies. Killing the Eyes and Mouths alone wouldn't have killed Zhaitan alone, but made effectively gave a debuff on him that made him vulnerable to more mundane methods, and we used the most effective of all mundane methods. It should be noted that the Pact canons and whatnot one-shot any normal dragon minion, such as can be seen in Camp Resolve or the first camps in Dragon's Stand, when mordrem get too close the canons fire and the mordrem die instantly. So those are really powerful canons (against dragons and their minions). Not enough on their own to kill an Elder Dragon, but they likely "bypass" the whole unique weakness thing by a good margin. I think Josso’s pattern still fits here, though it probably more generalized. Strength of the dragon is also its weakness. I’m not sure how Jormag and Primordus fit, unless it’s a simple fire/ ice scenario.Yeah I was gonna say, it doesn't seem like it fits them. Something that could make sense, though, is if they come in pairs: Mordremoth and Kralkatorrik's weaknesses are themselves; Primordus and Jormag's weaknesses are each other; what does that leave us with, for Zhaitan and Bubbles?
