Create your own achievement someone else could get. Make it actually hard, as in almost impossible. This is probably also going to be a "look what achi's I can get from here?" thread, but who cares?
There's no need to have already done your own achievement by the way.
I'll start:
"Defeat Amanitar, Jedoga Shadowseeker in Herald Volazj's room without letting more than 50% of the trash die outside of the room."