Slayer Dart is the only magical combat spell that can damage a turoth or kurask, along with the leaf-bladed sword and leaf-bladed spear being the only melee weapons and broad-tipped bolts and broad arrows being the only ranged methods that can damage them. The runes for Slayer Dart are also a reward from all Slayer Masters when you trade in points, doing so will provide 250 death runes and 750 air runes at the cost of 35 slayer points.