01) towers cost 60% of the original values while their upgrades 40%, mercenary units are 20% of the original values
02) heroes always gain bonus xp

01) game_templates.lua
tower.price = (substitute with tower.price = 0.6 * )
.price_base = (substitute with .price_base = 0.4 * )
.price_inc = (substitute with .price_inc = 0.4 * )
unit.price = (substitute with unit.price = 0.2 * )

02) game_settings.lua
GS.hero_level_expected: always 10
hero_level_expected_multipliers_below: always 2.50
hero_level_expected_multipliers_above: always 2.50