Complex sentence: Now it's almost gone and she plans to use the dragon eggs to restore the fading magic to her realm and then she would kill all the dragons, using their wings to cast a spell that will keep her alive forever.
Split into simpler sentences: Now it's almost gone and she plans to use the dragon eggs to restore the fading magic to her realm. She would then she would kill all the dragons, and use their wings to cast a spell that will keep her alive forever.