The energy spring must be a large one like the type that cities are established around while there is no requirement for the spring of life for them to fuse with and advance to rank 7 of the pathway of undying.
In order to prepare for this advancement requirement, they sent their slaves to gather information about these two objects. Their slaves went to locate them first before they began investigating everything related to them.
During their investigations they found the location of the spring of life and also discovered that the Vault of Gold is in control of it.
This means that in order to absorb the spring of life, they will need to fight a religious organization that prioritizes money above all else and is supported by a god. If they somehow succeed in absorbing the spring of life, then they would have offended the vault of gold and will be pursued by them.
