> At the moment one guy could make 4M idols by just farming from just first campaign, for example and then go throught then next 7 campaigns with a minimal effort.

While the effort might be minimal, this is the least effective method to get idols. The free play objective of the first campaign has the least gold reward and the least turnout of idols of them all as far as I am concerned. As a player you want to run the campaigns to enable the better Free Plays and to activate the post-20-slots. So, you really need to improve as fast as you can.

Also, with your suggestion, the number of received jewel chests would explode removing one of the main income sources for Codename.

In addition, how many different objectives do you suggest should be implemented to enable players to still unlock their talents (sorry, 'idols' was my mistake)? Bear in mind that repeating objectives other than free plays isn't possible.

All in all, Crusaders of the Lost Idols handles rewards, both idols and rubies, pretty fine from my perspective. It is an idle game after all and - very much like any other somwhat serious idle game I have seen so far - deals with its incentives like the others do too.