Suppose Cerberus is face-up at the Portal of Power. Prophecy is in play, so you draw 1 extra card. You land on the Portal of Power and draw Lord of the Pit, and now you have to fight both Cerberus and Lord of the Pit!
Both enemies have the same encounter number, and for each enemy you can choose whether to fight using Strength or Craft. I think you should have to fight both enemies with the same value (either both Strength or both Craft).
Now what happens if you encounter the Eastern Dragon and Lord of the Pit? The Eastern Dragon forces you to fight with your lower stat. I think you'd have to fight both enemies with your lower stat.
What do you think?