When some nodes become unreachable in your Akka-Cluster no nodes can take over their work or even leave the cluster anymore. To bring it back to a fully working state the unreachable nodes must be downed. However, if done incorrectly it could lead to data corruption, a split-brain, and a headache fixing it. In this talk, the open-source split-brain resolver called Lithium will be introduced. I will explain why unreachable nodes affect the cluster, the risks of downing nodes, and how Lithium recovers the cluster so it can proceed with all its duties.