Any race can be infected by the black crystal plague; however, the plague eliminates the original racial modifiers. The Eadon infected also have large black crystals that jut out of their body. The Akiya were released after the Eadon hive mind was destroyed, and as such no Akiyan was infected.

Ability score improvements. An Eadon infected can choose to increase any stat, which their original race would increase, by 2

An Eadon infected does not age after becoming infected, and as such spells that would cause aging effects automatically fail.

Eadon infected retain the alignment they had before becoming infected.

Due to the incredibly pain of the plague, an Eadon infected cannot regain hit points from a short rest.

Optimal fighter. The Eadon altered the physicality of its hosts, making the host the strongest they could possible be. When you level up, add the maximum value of your hit dice to your maximum health, and do not roll to increase it. Your ac also increases by 1 due to the crystals.

Though the Eadon hive mind was destroyed, all Eadon infected can telepathically communicate while within 500 feet of each other. Additionally, as a result of once being connected to the hive mind, Eadon infected cannot be charmed or frightened by either an aboleth or an Akiyan.

Because you are infected with the plague you have disadvantage on constitution saving throws against the poisoned effect.

While the crystal plague cannot be spread, your sickness cannot be cured by any means other than a wish. If your sickness is cured you lose all effects of being an Eadon infected and regain all racial abilities from your normal race.