Crowd-sourcing and testing Eureka Pagos NM spawn condition hypotheses

[Tsumdere]

Just out of curiosity I've checked your Lodestone to confirm a hunch and voilà: your guardian deity is Althyk, Umbral Earth and weak to Water in Eureka. Maybe spawners blessed by Byregot/Rhalgr or Thaliak/Nymeia would fare better?

Unfortunately, my main's guardian diety is Thaliak and I too have been having extreme trouble spawning King Arthro. Cool theory but probably completely false.