Perfect Harmony!

Ban beckoned for Eva to sit at a lotus position with her combat form. 

He then gives her the defective Beast Core for her to absorb it using the same method they used before. 

Eva placed the defective Beast Core in her tiny lap. The defective Beast Core was smaller than the Lord Grade Beast Core she absorbed before but it's still massive in size. Eva could only place it on her lap and it almost covered her stomach area. 

Ban went behind Eva and also sat in the same position as her. 

"Let's start, little Eva!" He said. 

They both closed their eyes at the same time as they started chanting the mantra that the Book of Techniques has provided. 

Before, the System said that Ban only needs to cheer little Eva to absorb and evolve successfully but he chooses to do it together with her now. 

He thought that the System might have just been messing with him at that time.