Nothing too hard about this boss use your preferred combat style and pray ranged. Thermonuclear smoke devil occasionally drops 1 dose prayer potions but I would still bring some spare prayer potions or super restores just in case you get unlucky on supply drops.
1 used to prioritize ancients for utility. 2 used to prioritize healing. 3used with set bonus. 4If using end-game berserker you can use the regular occult.