Miasmic Rush required a Magic level of 61 to use and could do a maximum of 180 life points per spell. In addition, any players affected by the spell who were using either Melee or Ranged style weapons would have their weapon speed halved for 12 seconds. As with all Ancient Magicks spells, the quest Desert Treasure had to be completed to cast this spell. The spell also required Zuriel's staff, making it one of the first Ancient Magicks spells to require more than just runes to cast. Miasmic spells, along with PvP Worlds and the accompanying Zuriel's staff required to cast them, were released by Jagex on 15 October2008. Players who had a Magic level lower than 78 would be required to use a corrupt zuriel's staff in order to cast Miasmic Rush as the regular version requires 78 Magic to wield.
The word "Miasmic" probably comes from "miasma", the gas that was believed to be responsible for plague and other diseases in 1700 Britain which actually didn't exist; plague was more due to rats and other vermin.
"Miasmic" could also refer to the Ancient Greek word 'miasma' which referred to blood pollution from killing those taking shelter in a temple, or killing family.