The next reward wasn't as impactful. 'Stronghold level +3' might sound great, but it wasn't essential as the current Stronghold level was still quite low, so it wasn't difficult to raise its level.
'Stronghold level +3' increased Starlight's Stronghold from low to intermediate — unlocking various facilities such as the 'Sentinel Tower,' 'Guard Tower,' and 'City Wall.' However, the production of them wasn't free.
The range of the Stronghold also expanded by one-third which was slightly better than the new facilities but at least it was better than nothing.
Other than these changes, the 'Hidden Reward' left Rhode slightly surprised. It didn't benefit Rhode directly — instead, it added a new structure called the 'Summon Gate.' Even in the game, it was considered a rare structure.