Guild Wars 2

I looked up for a recipe of the superior rune of the thief. I know you can buy crystal lodestones on tp, but how do you get them? Is there any mobs that drop it? Is there a specific dungeon for it? Maybe there is another way to get it?

I don’t have a direct answer but you can craft lodestones from cores using the Mystic Forge in Lion’s Arch and other places.

“crystal” makes me think of the Brand so maybe you can try higher level Branded creatures.