Cosmic runes can be crafted with rune essence at an altar on complexity 3+ dungeons by players with at least level 27 Runecrafting. Each action can use up to 5 essence, with each essence giving more runes based on your Runecrafting level. Make-X in Dungeoneering allows up to 50 actions to be performed, allowing a maximum of 250 essence used. Each crafting action grants 0.8 experience.