Monster activation - final battle question

I had a question about monster activation during the final battle. Last night, we drew a card from the Archivist's deck that allowed the hero to deal 2 wounds to the active monster. Is the dungeon lord allowed to know the contents of the cards prior to selecting the monster for the challenge? Or should the Dungeon lord select their monster group prior to drawing the challenge card? We assumed that the Archivist could select the monster group after learning the challenge type and contents of the card.

The FB is always read first giving the DL the choice of which poor creature will take the brunt of the pain listed on the FB card.

It wouldn't make sense to have the DL choose a monster before reading the card, because he wouldn't know what challenge type was coming.