Elder Dragons, which have a lot of power, can't be learned to max. Asuras, who are studying the Elder Dragon's powers, know a lot about that already.
-Let's talk about Zhaitan, old dragon, locked in depths of Orr, he was awakened from "Undead". Hard to kill, but.. lets talk about power. Zhaitan has power of Death and Shadow. Power of Death, makes him to control Humans, Asuras, Sylvaris, and all races, after they die. He take most of the minions from controlling dead races before he was awakened. Millions of people were Zhaitan's Minions. Power of Shadow, shadow gives him might, powerful power which only Dragon's can control it
-Mordremoth, Dragon of Plant and Mind, he take his minions through Mind, most of them were sylvaris, because they were weak on Mordremoth's call. But, Dragons have "other" powers, we we talk about them at end. Power of Plant.. its power of jungle, which he can control all plants in Maguuma.
Now, Jormag. Jormag is dragon from Ice, he lives in Far Shiverpeaks, which is very cold. Jormag is attacking the Norns, Norns are trying to keep Jormag away, but Jormag its too powerful. Jormag awakens in Far Shiverpeaks then he go south. Power of Ice, which can "control" Sons of Svanirs, and live in coldness. But no one knows his second power.
Primordus, dragon of first awakened dragon in tyria, Dragon of Fire. Fire has power to make his minions and "control" lava and fire. Primordus "makes" his powerful minions, which are destroying the surface of tyria.
And the last one, Kralkatorrik. Powerful Dragon which has power of crystals, which is making minions, and control crystals on his body to make clouds in sky, Kralkatorrik take his name from the volcano Krakatoa.
Glint, none of the online players know much about glint, but we know his descendant, Aurene, which lives in Forgotten City of Tarir. Glint is x20 smaller then Kralkatorrik. And no one knows about his power... Maybe, there are books in Divinity's Reach and other libraryes.
So. Taimi, genous, Asura, which knows that: Elders Dragons when die, like Zhaitan, gives his power to other Dragons, like.. Zhaitan gives power of Dead and Shadow to all dragons, so Mordremoth take minions from Dead Sylvaris. Now Zhaitan's and Mordremoth's powers belong to alive dragons. So, the point is, when some dragon die, all power splits to other dragons equal, and making more powerful minions, and dragon itself.
One dragon, which all believes his name is Kekai Kotaki, Deep Sea Dragon, which is not found, and its not still awakened. We just know that he lives in deep waters, and all believes that his name is Kekai Kotaki, but dwarfs thinks different. History of that dragon was burned, the book of "Kekai Kotaki". So no one know him.
Now, names of every dragon's minions:
Mordremoth - Mordrems
Zhaitan - Undead
Jormag - Icebrood
Primordus - Destroyers
Kralkatorrik - Branded
Kekai Kotaki - All believes that are Kraits.