Basically, I changed the UA version by removing the ability to use the Domain's 17th level capstone off the end of the wizards subclass, and added Domain's 1st level benefits at 2nd level.
Then spaced out the other abilities into the slots a normal wizard subclass would have filled.
Rationale: I didn't want a wizard to have the capstone cleric domain ability, I wanted that reserved for clerics. But I did want the two classes to have some similarity in the beginning.
In my campaign, these theurgists are called Magi, and "usually" chose Light or Nature domains.
Then spaced out the other abilities into the slots a normal wizard subclass would have filled.
Rationale: I didn't want a wizard to have the capstone cleric domain ability, I wanted that reserved for clerics. But I did want the two classes to have some similarity in the beginning.
In my campaign, these theurgists are called Magi, and "usually" chose Light or Nature domains.