The birds have defeated the Ice Shaman King and opened the gate to Burning Plain.
Choose Red in Paladin, Matilda in Princess and anyone as the third (either Piggy McCool, Pigiana Jones, Prince Porky or hire from Mighty Eagle's Mercenary). Every turn, attack with Red and the third one, then heal with Matilda. Ice Shaman King can use Whonk! to stun your birds. Be very careful.