I'm now playing on turn 50 on VH/VH with dark elves. I have "beastiary" building where they are suppose to manufacture Hydras and Black dragons but they are not available.
I did check the export_descr_buildings and in there it reads "and hidden_resource dragon" ??? What the heck is that, and where is it's location?

levels beastiary_1
{
beastiary_1 requires factions { spain, scotland, sicily, milan, saxons, byzantium, france, hre, venice, portugal, papal_states, russia, mongols, } or factions { england, } and hidden_resource dragon
{
capability
{
recruit_pool "hydras" 1 0.056 1 0 requires factions { mongols, } and hidden_resource dragon
recruit_pool "black dragon" 1 0.056 1 0 requires factions { mongols, } and hidden_resource dragon
recruit_pool "Dragon riders" 1 0.056 1 0 requires factions { england, } and hidden_resource dragon

I did actually delete that "and hidden_resource dragon" from the folder, but they are still unavaible. How I can acquire them? I really want to know.
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The other thing, DE economy.
With default settings player will have constant negative income due to all heavy cost upkeep units and ships. Test played this for 20 turns and no change.
I solved it myself by cutting every dark elf unit upkeep by -100 gold, and the for all ship types upkeeps I decreased from original 600 to 300. Only now DE economy is able to thrive.
Start is slow. but after few, 5 to 10 starting turns person is able to make economy to plus +2000 instead of -3000