Serdalis

I think the running theme has been that fern has built in stealth hax, since frieren struggled to find her before she could even suppress mana and the demon Lord couldn't detect her even using a flying spell right outside the window he was next to.

Also in the episode it looked like she was walking back to the two others as they were waiting expectantly and then she asks what now.

If the birds use mana as a threat reading above all else she could probably just walk over to it and pick it up.

Didn't she just pick it up cause she's super sneaky mana wise?

It's a reference to this comic https://knowyourmeme.com/photos/1314087-my-bike-got-stolen-recently

It's about economic damage, if they cost everyone else 1,000,000,000 in lost revenue, deployed assets etc, for the price of a few low cost missiles then they succeed.

Some map apps dynamically download the map for where you are so it would be blank in airplane mode unless it's preloaded