In the Rule entitled “Runes”, change the text

A Rune may be referred to by its Value.  A sequence of Runes may be referred to by the sequence of letters corresponding to the Values of its component Runes.

to

A sequence of Runes has a Value that is the sequence of letters corresponding to the Values of its component Runes. A Rune or sequence of Rune may be referred to by its Value.

A Rune Chain is a sequence of consecutive Runes.

Add a new Rule to the Ruleset.  Call it “Spellcasting” and give it the following text:

There are a number of Spells, listed in this Rule and its subrules.  Each Spell has one or more Activation Sequences, each of which is a Rune sequence containing one or more Vowels and no Damaged Runes.  Each Spell also has an Effect. 

Any Apprentice whose Workbench contains a Rune Chain that has the same Value as a Spell’s Activation Sequence may Cast that Spell.  Upon doing so, he must select one such Rune Chain, change the last Rune in that Rune Chain to a Damaged Rune, then perform the Spell’s Effect.

No two Spells may have the same Activation Sequence.  A spell cannot be Cast if its Effect could not be performed.