Cultist class - a variation of the cleric

In my Green Sea campaign setting clerics don’t serve a god, a pantheon of gods or other entities. They will be members of a cult. The abilities and powers are obtained after one organ is replaced by a “divine” organ. Each cult uses only one kind of organ, i.e. the order of the eagle replaces one eye with a silver eye. The transplantation is risky and only few survive this process. This organs are quite valuable to the cults and they will expend great effort to retain their lost organs. The knowledge to manufacture new ones is lost for some long time. The core ingredient for every organ is the same[this is not yet developed completely].

There will be gods in the campaign, but they will be more like the greek or norse gods. They are not locked in a distant plane, not infailable and not immortal. It is possible that a man could kill a god, but more likely will be that one has tricked one man, maybe multiple times and he didn’t even noticed it.
They will grant only individuals powers, but usually not a group that worshipping them.
That's why there will be no standard clerics in the campaign.

The cultist class is just an alternate version of the cleric and uses the same advancement scheme. The difference is that not every cult can turn undead, but instead they have other abilities. Also the weapon and Armour choices may differ from the standard cleric.
In the character creation the character already survived the transplantation. A Death Saving throw is necessary if a character becomes a member of a cult after the character creation.

Here are two examples for the campaign:

Cultist of the philosopher circle follow the standard rules for clerics with two additions. First they are immune to Ghoul paralysis. Second, the night after their death, they becoming ghouls. The brain is replaced by a brass brain.

Cultists of the order of the eagle can't turn undead. Instead they have infravision to a limit of 60 feet. Also, they can use all weapons. One eye is replaced by an silver eye.

In a later post I will detail cults with a little background.