Level 45 Slayer is required to attack Infernal mages and they give 60 Slayer experience. Remember that you must be assigned a task of them to get that Slayer experience.
Charm Drop Rates
Wear items that defend well against magic attacks such as dragonhide, splitbark, ahrims or mystic robes. They are weak against ranged attacks though melee works well too, don't forget your Black mask if this is a task! These drop numerous Gold charms, but on the downside they do not drop the other charms very often.
An evil magic user.
Black mystic hat, Black mystic boots, Lava battlestaff, Dragon med helm, Clue scroll (level-2), Rune scimitar, Starved ancient effigy
Bones (100%), Coins (1-29), Grimy herbs, Death rune (7), Earth rune (10-36), Fire rune (10-18), Water rune (10-18), Air rune (10-18), Mind rune (10-18), Blood rune (4), Body rune (10-18), Staff, Staff of fire, Gold charm, Green charm, Crimson charm, Blue charm