Both light and darkness give me the guidance I need. Thus... I can turn darkness into hallowed light! Behold!
"There is energy all around us. The energy is both yin and yang; positive energy and negative energy. Only a select few Firebenders can separate these energies. This creates an imbalance. The energy wants to restore balance and in a moment the positive and negative energy come crashing back together. You provide release and guidance, creating lightning."