"Gnoll tribes led by mysterious ogres are overrunning the few troops still defending the ruined wall."
Near the middle of the screen is a small Scout Camp apparently garrisoned by the two elves having a conversation in the cartoon intro panels. They provide supporting archery fire during the early levels. Archers deal low damage, but their fire rate is still relatively high, and they can attack both air and ground units. Every archer deals 10 damage.
Sadly, around level 10 their encampment is torched by a Gnoll Burner, opening a new channel between the upper and lower lanes. We weep for their sacrifice.