Description is incorrect this game has nothing to do with logic. Its very easy to figure out the solution to each level. The real challenge here is timing, you need quickly turn things to make ball bounce in perfect angles.
If you want to use Infectious Disease, then you should hold skeleton as distraction and run away. Even when skeleton get infected and die he will still buy you enough time to keep safe distance.
It increases your critical hit damage with all damage types including spells, unstable crits, random crits, sneak attack crits etc. Its also often nice to not have enemies attacking you the moment you step into LoS for some character builds.
I feel that last cube was at difficulty level that I would desired to play this. The most enjoyable levels for me were the early ones where you had a lot of rotation.
Sorry, I am not not very good with graphics ^.^ I hope it didn't hurt your eyes too much