Mura was a powerful asura who had a boon from Brahma. If Mura touched anyone, that person- mortal or immortal- would immediately die.
Mura was also the best friend of Narakasura, whom he always assisted in wars against Krishna. Mura had two sons and together they protected Narakasura’s capital.
With the special boon from Brahma, Mura and his sons were able to protect the city form many gods, including Indra and invaded many kingdoms. Mura even invaded Yama’s city.
Krihsna knew then that he had to intervene, he sent word to Mura that he was waiting for him at the seashore.
When Mura arrived, lord was gentle.
“ Tell me Mura, what do you want? Why are you causing trouble everywhere?”
“ I love to fight Lord. If you are ready for a battle, then let us fight. Otherwise please do not waste my time,” the asura replied.
“But I am scared Mura, said Krishna, pretending to be afraid. How can I fight an asura who has chased away the likes of Yama and INdra? My heart is beating loudly. I think I can hear you heartbeat too loudly. Are you frightened too?”
“ of course not.”
“But I can feel it. You heart is clearly trembling.”
“ it is not,” said Mura and placed his hands to his heart to check. The boon that Brahma had given him came to play and before Mura could realise, he lay dead on Krishna’s feet.
From this day on, Krishna also came to be known as Murari.
(While reading many stories I have realised everything is a grand play. Lord will grant boon to asuras and then create a gameplan to kill them)