Why does the creatures expansion only include one blue banner? What if I want to use the hydra and the blue widow spider at the same time?

Because they want you to buy Dragons also and borrow that blue banner?

Actually, I just noticed that the scenario "Spider River" included with creatures has two giant spider figs on the board at the same time. I'm sure there are a few out there with two base sets, but the rest of us are out of luck. Yes, I saw the note to sub in the wood giant if needed, but the objective of the scenario is to kill both spiders...