Dominions 3: The Awakening/Magic/Magic Gems

Magic gems are condensed magic energy and seven out of the eight paths of magic has gems while Blood magic has Blood Slaves. Magic gems are used to fuel rituals, powerful battle spells and in forging magic items. Mages can also used a great number of gems of aproriate type to gain a permanent level in magic (called Empowering)and they can use them in combat to quench fatigue caused by spellcasting. A mage in combat that has a gem that is of same type as one of his magic picks gets a +1 bonus to that magic pick in combat. For example, a Nature 1 mage with one Nature gem would count as a Nature 2 mage while making spells. Only the first such gem per cast counts so a Nature 1 mage with 2 nature gems still counts as Nature 2 mage.

In addition, with battle spells the use of gems reduces fatigue; if N extra gems are consumed during casting, fatigue from the casting is reduced to 1/(N+1) of normal. Battlefield spells which cause at least 100 fatigue all require the use of one gem per 100 fatigue.