From the Introduction:
This magic system is an open system allowing players to create and customise their spells within a framework to maintain rules integrity. This is achieved by using a 'magic' language made up of runes. By putting together a logical group of runes a character can create a spell.
Casting runes involves a somatic and verbal component for each rune used in a spell, in addition to this some of the runes used, mainly the runes that give the spell its power, require a material component as well. Also to limit the number of spells a magic user can cast each rune cost the player a power point to use, each player having a predetermined amount of these power points, dependent on the characters level of experience in runic magic.
So to successfully cast a spell involving a number of different runes a player has to go through a reasonably involved process, the more powerful the spell generally the more runes so therefore a more involved casting process.