Not sure if it’s intentional design, a bug or beta placeholder values, but currently the special mission modifiers and secondary objectives give the same rewards only modified by difficulty level.
For the secondary objects, I don’t mind at the moment, since you get partial rewards scaling to how much of the secondary objective you complete.
For the mission modifiers you get the same reward running a ‘fewer hordes’ modifier (that makes the mission easier) as you do a ‘darkness’ or ‘more hordes’ modifiers (that makes missions harder).
Rewards other than xp/dockets for modifiers/secondaries:
Shop refresh token
Modifier token (add/remove modifier(s) to map)
+Chance or guaranteed Emperor’s Gift (melee/ranged/curio/specific)
Contract currency
Contract refresh tokens