When you get this perk (necromancer career tier 3 perk 4) the game enters a state of being entirely unable to promote the basic skeleton.

This seems to happen because the 50% reduction gets applied to a cost of 1 and gets rounded down to 0. And then the game doesn't know how to deal with a cost of 0.

It is possible to toggle the state on and off by selecting and unselecting the perk in the career menu.



Detailed description of the issue.
This picture[i.imgur.com] shows how there should be 9 skeletons abailable for upgrade the indictor for upgradeable troops doesn't show up.

If I click the button to upgrade skeletons the game freezes and triggers the crash watchdog.

In the Upgrade Troops sub-menu the Skeleton entry does show up but it doesn't react to mouseover and the buttons to actually perform the upgrade are un-clickable.