The Church of Universal Truth teleported and then detonated it’s follower worlds to open the Fault further as Adam Magus and evil Quasar welcomed their lord. Upon his discovery that Thanos was still alive, Thanos being the avatar of death, he promptly kills Adam Magus before being revealed to us as Mar-Vell from the other side of the Fault.
His mission? To kill death. That means Thanos is now the key to everything.
