If there is a rule entitled “Runes” that contains the sentence “The legal Values for Vowels are ‘A’ and ‘O’.”, then change that sentence so that it reads:

“The legal values for Vowels are ‘A’, ‘O’ and ‘U’”.

Add a Rule entitled “Unstable Runes”, as follows:

The Vowel ‘U’ is a special magical element, not found in nature and only obtainable through the artificial process of transmutation.  If any Apprentice has the sequence “AAOO” or “AOOA” in his Workbench, then as a Daily action (and so long as that Apprentice does not take any other daily action during that Day that involves making changes to his own Workbench), that Apprentice may substitute “UUUU” for the “AAOO” or “AOOA” sequence in his workbench.  Notwithstanding anything to the contrary in the ruleset, an Apprentice may only voluntarily obtain instances of the Vowel ‘U’ to his workbench by operation of the previous sentence.

The vowel ‘U’ has a short half-life.  If an Apprentice (the “U-bearer”) has one or more ‘U’ runes in his Workbench then any Apprentice may change the rightmost ‘U’ in the U-bearer’s Workbench to ‘X’ (this process is called “U-Decay”), so long as the Apprentice making that change makes a comment to the GNDT expressly indicating that he has done so, whereupon a minimum of three (3) Days must elapse before the U-bearer’s Workbench may again be subjected to U-Decay.