A new Runecrafting/Agility/Construction activity would be pretty awesome. I'm imagining something where you actually go inside the source of the altar's power (construct some planks on the stonehenge structures, activate the altar and jump in using agility) to go to a new training area. The training area will be floating over an abyss. New platforms continuously appear, and orbs of colored energy flow towards the center column. You must jump around making sure that only the colored energy that corresponds to the rune you're making makes it through. You do so by building filters: red energy that goes through a blue filter gets completely destroyed, but orange energy that goes through a red filter turns dark red. For every correct energy that goes into the center, you gain RC XP equal to the rune, and if you power it enough, when you leave there will be a reward that is lying on top of the altar for you to take. It can range from new rewards such as *real* law and nature battlestaves to catalytic runes. The main reward is a rune pouch that can hold an unlimited number of runes and spells can be cast from inside of.