To create a living avatar of himself which will continue as the sect master even after he is gone. As much as Cyrus would love to rely on his sect members and the other gold realm masters left behind to protect the empire, he just couldn't do that.
He has seen the way Demos creates avatars bearing his consciousness and this seemed to be the only way he could leave but also stay behind to protect his sect.
To accomplish this, Cyrus needed two things. Firstly was the ability to split his consciousness and allow that fragment of his soul exist outside his body for a long while. But this wasn't a problem for Cyrus since unlike other people, his life magic granted him abundant life force and a very powerful soul. That's why even in death, Cyrus' soul would be able to exist and search for a new body. The main problem he encountered was the second requirement.