Complex sentence: On Tiala's 16th birthday she receives a red jewel, which unbeknownst to her has the power to awaken the great dragon, which legend has it can grant eternal life to one who drinks it's blood.
Split into simpler sentences: On Tiala's 16th birthday she receives a red jewel. Unbeknownst to her, the red jewel has the power to awaken the great dragon, which legend has it can grant eternal life to one who drinks it's blood.