What's an Inert Fire Crystal, you ask?

Simple! See, a Fire Crystal takes a long time to gather heat on its own. These crystals that are still in the process of gathering heat appeared mostly in the wilderness around Haven, and when the Knights landed, they took a lot of samples for study. Once they started to develop a method of putting heat into these Inert Fire Crystals, Kozma bought out a whole lot of the ones still on the market. Now she's cashing in, big time! They have a tendency to shine in light, but being Inert, they still have no light of their own.

Inert Fire Crystals of varying quality are found rarely from Treasure Blocks, normally at a few higher depths (altitude wise) than their less inert counterparts. They can someties be retrieved after a failed Forge attempt. But the biggest source of these Inert crystals are from Kozma, who sells them at 1/4 the price of the usable Fire Crystals of the same level.

The star levels are as follows:

0*: Opaque Inert Crystal
1*: Thick Inert Crystal
2*: Glittering Inert Crystal
3*: Reflective Inert Crystal
4*: Shiny Inert Crystal
5*: Dazzling Inert Crystal

So how to make these Inert Fire Crystals into usable Fire Crystals? Simple! Plop a stack in the new "Fire Crystal" slot on your Equipment. There, one crystal at a time will gain heat from doing stages in the 'Works.

However, you can only heat one Crystal at a time. HQ had some Biotechs try to heat more than one. It ended with a lot of severe burns. And I mean a LOT of severe burns. While those brave, selfless souls sustain even more severe burns trying to figure out the method of heating more than one Inert Fire Crystal, you'll just have to stick with one so you can fight properly.

Replacing the Fire Crystals in the stack causes any heat currently in the Crystals to vanish. When a crystal is heated, it automatically removes one Inert Fire Crystal from the stack, and adds an equal-levelled Fire Crystal to your inventory; you cannot heat more than one Crystal at a time. While the typical level might be up in the air as to providing the necessary heat for your Fire Crystals, levels like Firestorm Citadel, Danger Missions or Arenas should be enough.

Now what purpose do these crystals serve? Simple: by putting in some effort and a smaller amount of energy, you get cheaper item heating. Meanwhile, OOO still makes money because the majority of the Inert Crystals will be bought from the Supply Depot at 175 E per stack of 50. Win-win!