In the end, Min and Erla chose a random guy named Habac. He was only one stage higher in cultivation than Rean. He was also part of the humanoid races, but not a human like Rean. Instead, he was from the Dry Vein Race. The reason for this choice was very obvious. The Dry Vein Race was famous for being able to absorb more Divine Energy than those at the same level. It was as if their veins were always thirsty for more Divine Energy, thus the name. Unfortunately, that didn't make their cultivation speed any faster.
For Rean, the guy was perfect. The battle formation had a high requirement for Divine Energy, just like Roan mentioned. Someone who could absorb more Divine Energy would help their group a lot more.