Sorcery is the use of runes expressed through skill to create magical effects.
A spell may not contain more different runes then the sorcerers Mental Agility (MA)
A spell may not contain more runes of a single type than the sorcerers Mental Strength (MS)
A spell may not be cast over more rounds than the sorcerers Mental Endurance (ME).
Up to MS+MA runes can be expressed per round. If the skills involved use only the Physical attribute of either, or both, types the character may use the Physical value. Longer spells continue the casting in the following round.
eg. Skuul, the firebolt slinging monk, knows the Fire rune expressed via Incantation (Fire [Incantation]), and the Distance rune expressed via his martial arts (Distance [Kung Fu]); Performing a short kata to invoke Distance, and chanting 'Nekuodah', hurls a bolt of fire from the monks hands at a nearby opponent.