When all the Vorpp items dropped for me I accidentally deleted the Focusing Crystal because I thought it was a standard event trash trophy until I noticed the two others. I have yet to have this item drop again so I can’t get the achievement. I noticed they’re soulbound, so can different characters get their own copies of the items or are they an account based drop?
Edit: Nevermind, it suddenly occurred to me to go talk to Vorpp and see what happens and it gave me the achievements when I did. Should’ve tried the obvious before posting.
Achievement progress is triggered/completed on picking up the 3rd & final item from a mob drop, once that’s done, you can go see Vorpp and continue his meta
(and happily delete the trophies)