Magic Gems

Magic Gems and their usage
Magic gems come in all the eight different types of magic: Fire, Water, Earth, Wind, Astral, Nature, Death and Blood. Astral and blood magic have unique resources called "pearls" and "slaves" respectively and aren't technically "gems", but are generally used in the same way and the game mostly refers to them as "gems". Commanders can be equipped with gems from your nation's stockpile and carry them in their inventory, but they can only be withdrawn or deposited if there is a lab present in the territory.

These resources are necessary for nearly all forms of magic, and they are always expended when used. There are four different ways to use magic gems: Rituals, Spells, Empowerment, and Alchemy.

Rituals are a powerful form of magic used outside of combat, and every ritual regardless of which school of magic it comes from needs magic gems as the fuel to cast them. When a mage performs a ritual they must either be in a territory with a lab, or have the necessary number of magic gems within their inventory. If a lab is present then the mage uses up gems from its nation's stockpile, otherwise the gems in its inventory are expended.

Spells are magic cast during combat. Although many spells do not require magic gems to be cast, most of the more powerful spells have a magic gem cost. Mages that want to cast spells that cost magic gems must have gems equipped in their inventory when the battle starts, as they can only use the gems that they're currently equipped with.

Empowerment is a way to permanently improve a commander's magic level within any of the magic types. The cost of empowerment depends entirely on how high the commander's current magic level is regarding the specific type. For example, in order to raise any commander's magic level from 0-1 the cost is always 50 magic gems. In another example: if you want to make a regular military commander capable of leading undead troops, you must make them proficient in death magic. Thus, empowering that commander to level 1 in death magic costs 50 death gems.

Alchemy is a way of transforming magic gems into astral pearls, or astral pearls into magic gems. All magic gem types aside from blood slaves can be used in alchemy, and the cost of alchemy is alway the same. It costs a total of two magic gems to create one astral pearl, and it takes two astral pearls to create one magic gem. For example: if have zero death gems, but you need ten for a ritual then you can use alchemy to transform other magic gems into death gems. Gems can't be directly transformed into other gems, instead they must first be changed into astral pearls and then further into gems again. Any mage can use alchemy, but they must have access to a lab.

Where do they come from?
Magic Gems can be gained randomly through events, but the reliable method of acquiring gems is through magic sites. Most magic sites produce magic gems each turn, and the owner of the territory that the magic site is in receives these gems each turn if there's a lab either in the same territory or a connected allied territory.

There are magic sites that produce blood slaves, but the more reliable way of collecting them is by having a mage who is proficient in blood magic perform a blood hunt in a populated territory.