After a server reaches a certain age, you can upgrade certain buildings over level 30 by using fire crystals.

Upgrading your camps over level 30 by using fire crystals grants you fire crystal troops.

All your troops will automatically be upgraded to fire crystal troops once you completed the upgrade for the respective camp for each troop type. There’s no need for additional troop promotion to get fire crystal troops.

Each level of fire crystal will give your troops bonus stats and at the fire crystal level 3 your troops will acquire an additional skill. At fire crystal level 5, this skill will be upgraded getting stronger.

• Infantry

• Lancer

• Marksman

Since Fire Crystal upgrades affect all troop tiers, I’ve made a little table to show the comparisons of all Fire Crystal tiers on troops T1-T10.

https://docs.google.com/spreadsheets/d/1gWxfVCFR_iaYeUYY9mXurvXIFwqKXPG3qeuJFaSvjRk/edit?usp=sharing