Infernal magi are Slayer monsters that require level 45 Slayer to kill. They are sometimes killed for their common death rune drops; otherwise, these monsters are usually neglected, even with their frequent gold charm drops, as most monsters have better charms rates.
Infernal magi are a good source of death runes, and are the only monster that drops dark mystic hats and boots.
Infernal magi use a weaker version of the spell Fire Blast to attack the player, so wearing dragonhide or mage armour will reduce the damage taken. This attack hits a maximum of 220 life points, but hits extremely often. Protect from Magic is recommended. Bones to Peaches is recommended, too, as the bones they drop can be converted to food. They are weak to arrows, so it is advisable to bring the best bow available.
If a player stops fighting and lets a familiar attack the infernal mage, the mage will attack back with melee, no matter how far the familiar is from the mage. You cannot use a Dwarf multicannon on any infernal mages due to the fact that they are only found in the Chaos Tunnels and the Slayer Tower, and neither of them allow the use of cannons.