If something is simoniacal, it has to do with buying or selling religious things or positions, especially in a way that is not honest or fair.
Simoniacal things are usually thought of as very bad and dishonest.
Examples:
The simoniacal priest was punished for his actions.
She was accused of simoniacal behavior.
The simoniacal sale of church offices was a serious crime.
He tried to make a simoniacal deal with the church.
The king's simoniacal actions angered the people.
The simoniacal scheme was discovered and stopped.