There was an open tome that laid before any student of arcane magic to browse, though heavily guarded in the archives of the Kirin Tor.

Farna, Covos, Rexthis, Malar. These are only a few of the runes one might use to channel the power of the Arcane. Runes that surely my predecessors have found great value in exploiting for their endeavors. But my theory has proven true, I have successfully performed great lasting feats of magic by programing additional formulae into each of these runes. I dub them "puzzle runes." I suppose one better example of how this process works is to take Farna, the rune of fire. Using this most basic rune, a sorcerer might meditate on a complex series of formula in layers within the rune. (which, used here, acts as a catalyst for even greater magics.) Casting the rune of Farna with the layered formula, and utilizing the sheer power of one's will, you can force an explosion, erupting your target into flames and allowing your formula to pull in the surrounding energy, to keep the flame burning evermore.

Lasting flames, Arcane magics that transform within the formula...sheer brilliance. What's more, if the formula is layered correctly with a multiplier at the middle..your rune will not be easily dispelled by weaker magics.

-From "The Theory of Puzzle Magic" Chapter One
By Kael'amand Solarwing