I like very much Kingdom Rush. I have a problem with the reinforcement: I Upgraded the reinforcement to the max (Spear Throw) but in the battle the legionnaires can't target flying enemies ... ???
Yeah there's a really weird bug in the game, where on some levels you can't use all your upgrades. Say, even if you max out the meteor skill on some levels the last couple upgrades will simply be bugged and not work. It's actually a really annoying bug for me because you can't know what levels don't allow what upgrades.
its not a bug.... Read the rules of each Special Mode(Iron, Heroic) before you play. It's not a bug, it's a feature. We won't fix this, so don't expect that we fix or change this.