Choose sunken temple as your base if you want eldritch. Choose gold mine as your base if you want daemons.
-.- ... After you have chosen sunken temple or gold mine you get options to explore deeper parts in these bases. You can find your chosen allies in these deeper parts of your base. Cannot remember if you got option to explore these immediately after you have claimed these places or it toke some time like with Malagar before you get the option. I think eldrich wants priestess and Daemons want sky elf. I have not played with these factions so I don't know much about them.