Crossworlds : how are trophies working?

[marc]

Can anyone tell me how I'm supposed to gather trophies for the military academy in Crossworlds? I've cleared two islands so far without getting a single one. At first I thought that maybe it was because monsters were weaker than me, (I map kited a bit) but even Lethal and Very Strong stacks didn't give me a single trophy.

I have the regalia properly equipped for all fights. Is it because I had it "modified" by the demon trainer so it can grant me demon units?