Miach is the Irish God associated with restoring the lost limb of the High King Nuada. He replaced the silver arm his father made for Nuada with an arm of flesh and blood. However because of that his father killed him out of jealousy for being able to do so when he himself could not. He did so by chopping Miach's head four times with his sword. The first strike only cut Miach's skin and Miach healed it. The second blow broke Miach's skull but Miach also healed that. The third cut grazed Miach's brain yet Miach could even heal this. The fourth attack cut his son's brain in half and finally killed Miach.
This resulted in 365 herbs growing from his grave one for everyday of the year and one for every illness. Miach's sister arranged and catalogued them all but their father was angry for being out done again so he scattered all the herbs and all of the knowledge on the herbs healing properties were lost forevermore.
This is a reflection of the belief that the plants that grow on a person's grave hold some of their spirit and so what grew from the grave of the healing God were all the healing plants in the world. Of course being a God his death was not permanent and he appears later in the battle against the Fomorians side by side with his father and siblings healing the wounded of the Tuatha Dé Danann at his father's famous healing well so it seems like there were no hard feelings in the end.
Miach can be honored today for any medical procedures surgery or healing over period of time. Offerings to him might include herb - infused water herbs associated with healing or pure water.