Question: hxh how did the king die?
Answer: Then he (Netero) pierces his finger into his heart and the Miniature Rose [nuclear] bomb goes off. It severely damages Meruem and poisons him. Then Methuthuyoupi and Shaiapouf give Meruem their Cells And Nen and Meruem is healed. But later on Meruem dies because he is poisoned with the flower bomb.