None of those godly items was below level-16, for level-13 was the beginning of godly miracles. The mages would have been barely able to use any of those items when backed by equipment, provided they were compatible.
If they reached level-16, they would be able to use all six at once.
The six godly items were the Book of Gaia, the Well of Stars, the Dimensional Staff, the Scorching Candle, the Deathly Night and the Tears of Light.
The Deathly Night was the core of the six godly items, which corresponded to the power of dark element. It was also the most powerful. It was also important, however, to take the enemy's environment into account.
If fighting in the sky, the Deathly Night would have been the most suitable choice, but since mages were deep underground where earth element was the most abundant, they would have been able to bring out more of the power of the Book of Gaia.
