The Spiked Seven Arrow Book was a curse spell, and all curses were the most powerful divine abilities of the primordial era.
It was difficult to cast easily. For example, the the Patriarch of the Heaven sect's Six Soul Banner was also a type of curse spell.
To a certain extent, the power of this curse spell even surpassed that of a numinous treasure.
However, every curse spell wasn't something that could be cast easily.
In truth, Dao Lord Lu Ya's battle prowess was only on par with Zhao Gongming's. He might have been slightly stronger than Zhao Gongming, but he definitely wouldn't have been defeated so easily. However, by relying on the Spiked Seven Arrow Book, he had been able to kill Zhao Gongming by force!
The Spiked Seven Arrow Book was a book that recorded spells, and it was also the foundation for using spells.