Okay I get that these are totally random but are you more likely to get them from clearing a rift, finishing an IA. Does it matter your level...ie level 50 clearing a level 20 rift, or level 15 mentoring down to 14 and doing IA's in silverwood. Are the chances all the same? Is there anything that will increase your chance of getting one?
Or is it truly completely random? I wonder because I got one at like level 13, I am now level 50 and have never gotten a second one.