A large case series and systematic review mapped a rare but deadly triple immune-related toxicity involving the heart, muscle, and neuromuscular junction in cancer immunotherapy patients. The work described clinical patterns, treatment behavior, and a high-mortality profile, emphasizing the severity even when the toxicity is infrequent. The report provides a structured clinical picture for monitoring and differential diagnosis, particularly for patients presenting with overlapping symptoms that can otherwise be attributed to infection, progression, or separate immune adverse events. For immunotherapy developers and treating oncologists, the mapping highlights the need for clear recognition pathways and management strategies when immune-related toxicities cluster across organ systems.