Exactly as it has been said however I can break it down even further. Around the soulforge in the royal city (not the one in the queens house) are quest givers that ask for imbuing ingredients. 50 magical residue quest = +10 imbuing powerscroll and a chance at getting a random runic mallet and chisel. 50 enchanted essence gives a +15 scroll and a chance for a runic again, I have not done the relic fragment quest as of yet but I can venture a good guess as to the reward. As far as I know now, the chance of getting a runic does no increase with the higher level ingredients, acting much the same as the runic rewards from heartwood. I hope this helps.