I've seen many beginners get confused when their second Ectoplasm takes them from 7 to 5, thinking that the -2 hand size includes the first ecto. I think it could be a subtitle a la Oops! All 6s, to show something like:
-2 hand size
(current: 7 → 5)
This would also make it slightly nicer when you find an ecto in ghost deck's shop and don't remember your hand size