Cosmic rune

Ironman verdict

At least 9 monsters drop it. The easiest is Dark wizard (level 9, 1/128); the best rate is Ghostly warrior (level 61), at 15/128, about 1.8 per kill. You can also make it yourself: it takes 27 Runecrafting and gives 8 Runecrafting XP, using Pure essence. There is one other recipe below. Other sources include Gnome Restaurant, Essence impling, Essence impling jar and Professor Onglewip, plus 4 more listed below. Making ten takes 10 × Pure essence and gives 80 Runecrafting XP. Reaching level 27 Runecrafting takes 9,730 XP in total; the Runecrafting calculator counts the actions and materials to any target, and the Runecrafting guide has the Ironman training route. 93 recipes use Cosmic rune, including Air orb, Alteration necklace and Amulet of bountiful harvest (new). Cosmic rune is available on free-to-play worlds too. It is tradeable on normal accounts, but an Ironman cannot use the Grand Exchange or trade for it, so the sources on this page are the whole list. High Alchemy turns one into 46 coins, which is 186 less than the shop price, so buying it to alch does not pay.