Tzadikim are G-d's Partners

 Ramchal (Daas Tevunos 158.8) And see how much honor the Creator, G-d, gave to the tzadikim, whom He considered to be partners with Him. Because He truly gave them a part in the correction of the world and the perfection of creation.until we find the correction of creation, so to speak, divided between G-d and the tzadikim, which is not fulfilled except by both.

Ramchal (Daas Tevunos 158.13) And now we will explain the reality of the partnership that we mentioned between the righteous and God in the correction of creation in that G-d provides benefit only according to the preparation of tzadikim.  It is therefore best if the tzadikim increase preparation upon preparation and correction upon correction, and correspondingly G-d will send benefit and elevation.