Non-Awakened can't use Spirit Magic, so they split everything into smaller, more controllable steps. That's why they need the runes and the magic circle. The mana is compressed by the runes into a sphere and then injected inside the vessel; there is no compression nor a pseudo core, just runes.
The runes drawn between the circles form an energy sphere, absorbing and injecting mana from the surrounding space into the item. Every single rune requires its own spell to be engraved into the object (plus another spell to permanently imprint the energies into the item), and each spell must be cast in rapid succession without delay, as mana tries to escape as soon as the magical furnace is loaded. The circle usually destabilizes after 10 seconds, after which mana begins to leak. The forge mastering process cannot be repeated if it fails after the object is saturated by mana, as the energy remnants from the previous failure linger. The runes are used to create and stabilize the mana pathways, but disappear once the process is over.
Embedding a crystal into an item is a delicate and irreversible process. Once one or more crystals are embedded, the Forgemaster no longer channels their magic directly through the object, but through the gemstones instead, which act as magical conductors that widen the time window for enchanting an item from a few seconds to a few days, depending on their strength. Crystals also act as a power source, allowing use of multiple spells in a short time frame with no mana expenditure from the item's user.
Infusing Elements
Magical objects without elements infused into them are called neutral items. Giving an object elemental properties cannot be done without ingredients. This is one of the few cases where forge master's overlaps with Alchemy, but unlike in Alchemy, where ingredients are necessary to absorb the element and store it for future uses, Forgemastering does the opposite since it aims to create permanent objects.
Infusing an object with an element requires the Forgemaster to purposely alter the balance of their spell in favour of the chosen element, which causes the final product to be slowly eroded by the energies that empower it until it crumbles or explodes. To prevent this, a counterweight ingredient is needed to restore the balance (i.e. if infusing the fire element, use a water-based ingredient to counter it). The stronger the intended effect, the more powerful and rare the ingredient usually is. Infusing multiple elements has the same requirements as performing multiple enchantments.
However in fake Forge Mastering, the ingredients don't restore the balance by simply countering the element energies during the enchanting process, they actually pass their pseudo cores. Due to this, multiple enchantments require multiple pseudo cores coexisting in the same item.
True Forge Mastering requires not to shape the core, but to build it with the proper set of runes according to one's needs. To overcome the limits of fake mages, one must imbue the runes made out of Spirit Magic with one's willpower, or the mana will fall apart. Tier 4 true Forge Mastering is identical to that used by fake mages.
Pseudo Core
Forgemastering is about creating pseudo mana cores that are engraved onto an object, then stabilized by precise mana patterns that feed on world energy for self-sustenance and prevent the core from dissipating. Pseudo-cores have no consciousness, just a purpose, and unlike mana cores have no way of replenishing their energies without the mage that imprinted them.
Forge Mastering requires a lot of mana because objects offer tremendous resistance to external energy. The more complex and powerful the artifact, the more complex the pseudo core has to be. Second attempts at forge mastering are useless because every rune leaves a carving, and a wrong pathway for the mana can render the object useless. The more enchantments added, the more complex a core becomes and the more energy it requires until it's more efficient to shape another one as it happens for elemental weapons.
Objects can have multiple pseudo cores embedded in them as well as mana crystals. The only way to prevent destructive desynchronization when accessing them is to imitate the mana signatures of the crystals and inject mana into the pseudo cores every time they go out of phase. Multiple pseudo cores require their user to know how and when to activate one or more of them at the same time whereas a single one once activated follows its program until it is turned off.
Mana Pathway
Mana pathways are artificial energy conduits that anchor the pseudo core, trapping its wild energies in a loop that prevents them from being dispersed due to a magical item's inanimate nature. The number of necessary mana pathways depends on the pseudo core's strength. Too few and the mana forming the core is dispersed, too many and it crumbles.
Power Core
A power core is the sum of multiple pseudo cores, capable of coordinating and mixing them to obtain a number of effects greater than their sum (e.g. a power core with fire and wind makes a flame tornado from the 2 skills).
Mana Amplifier
A mana amplifier is an ingredient that any Forgemaster can use which allows them to amplify their mana to hold one's own energy signature. Amplifiers are typically parts of the body that have been refined. Forgemasters can use their own blood, feathers, or scales to convert foreign energy signatures as well. However, the longer a piece of a body has been infused with mana, the more powerful it becomes. This means that even the amplifiers of someone who has lived several centuries aren't much compared to those of creatures that lived millennia.
Just like how magical metals are just earth purified of its weakest components turned magical after being subjected to a powerful flow of world energy for a long time, the same can be said about the bodies of Awakened, be they humans, Emperor Beasts, or Divine Beasts. Until the blue core, their bodies still have impurities that limit their strength and mana flow. Past that point, energy and matter mix, transforming every part into a powerful magic conductor. The problem is that, unlike an enchanted metal, Awakened's bodies starts much weaker and it takes a long time for the mana flow to temper their flesh. The violet core level is the optimal level of body refinement for Forge Mastering because the lack of impurities makes the use of Origin Flames unnecessary and the materials lose no mass during the rest of the procedure.
The corpse of a powerful Awakened and magical metals are similar, to the point that they can mix akin to what happens with the Bonding spell for magic crystals. The procedure requires a crucible big enough to host all the materials and to melt the metal.
Fake mages don't use amplifiers because their short lifespans and inability to refine their bodies prevent them from having decent amplifiers. Awakened have amplifiers, but it is not exclusive to them. Amplifiers use parts of their own bodies (e.g. feathers, scales) because pieces from the others alone will provide the wrong kind of energy otherwise.