Can you use {jace's archivist}'s ability in response to your opponent playing a creature to counter it? If it's on the stack it's not in your opponents hand anymore right? Would you literally have to announce the ability before your opponent taps mana?
When a spell is being played, it is no longer in its owner's hand (it's on the stack), so {Jace's Archivist} will not counter it.
Even more important: PW abilities are played at sorcery speed and only on your turn.
Ignore me. I saw Jace and thought planeswalker.