I'm finding around levels 11-14 that things like Stun, Charm, Knockdown, etc. are just not working anymore. Either the enemy is immune or they make their saving throw. It's gotten to the point that the best way through a battle is to just forget tactics and just whack something till it's dead.
I really hate it as I liked changing things up in battle, but it just isn't worth wasting AP anymore on trying.