Long family in another world

in a suicide mission of killing his father, he accidentally killed his sister too. But not to worry. God gave both of them a second chance. They transferred to another world. God granted their three wishes. The sister became a overpowered water mage and the brother asked for knolage fore both of them. Wait what? Why knolage? How is it going to help them survive? The brother said,"I will become the overlord with your cheat sis. But I don't wanna be." Little did he know, his destiny is something surprisingly superior.