Buy RS3 Chaos rune
The chaos rune is a catalytic rune in RuneScape 3. It powers bolt spells and some Curse spells. Free players can use chaos runes, so they are not locked behind a membership.
Chaos runes are the key rune for medium level combat magic. You need one chaos rune to cast Wind Bolt at Magic level 17. You also need one for Water Bolt at level 23, Earth Bolt at level 29, and Fire Bolt at level 35. The rune is also used for Crumble Undead at level 39, a spell that works well against undead monsters.
Chaos runes are stackable, so a big supply takes up only one spot in your inventory or bank. They weigh nothing and they are tradeable. Members can craft them with the Runecrafting skill at level 35, but making them by hand is slow. A ready stack lets you skip that grind and cast bolt spells right away.
If you train Magic with bolt spells or fight undead with Crumble Undead, you will burn through chaos runes fast. Keeping a large stack on hand means your training never stops because you ran out of runes.