how many flags you can build without crystal in LK?

■flag cost in LK

you can build first 20 flags without crystal in LK.  from 21th flag, you need crystal,  and the cost increase rapidly.

see  https://rok.guide/flag-building-costs-kvk/

the flag cost depend on "current number of flags",  so if you remove some flags,  the cost decrease.

rss cost in LK is much smaller than main lands.

■fortress cost

https://riseofkingdoms.fandom.com/wiki/Territory

fortress1 is much cheapter than 2.  

you can reduce cost by demolish ALL(2) AF in main land before building new AF in LK.