This story takes place when our lovely Elena and Caroline started their Whitmore college journey and The Originals were facing threats by The Witches and when Hayley was pregnant with Klaus's child.
This is all about a vision which took place in 1600s in Greek to a Witch that if at the next Solar Eclipse which happens every 400 years a Vampire is created that day he would posses the power to release an Ancient creature. Who is also known as myth in some places.
Only The Originals, knew about the truth and some Ancient Vampire's who had been working for Original's and one of Elijah's most trusted vampire knows about this vision.
This creature was created before Qetsiyah and Silas invented immortality spell.