Complex sentence: Theodora enters Glinda's domain and angrily reveals her new, hideous appearance to Oscar before threatening to kill him and his allies with the Emerald City's well-prepared army.
Split into simpler sentences: Theodora enters Glinda's domain and angrily reveals her new, hideous appearance to Oscar. Shethreatens to kill him and his allies with the Emerald City's well-prepared army.