try for the knight always attack speed, attack, and hp. for archer upgrade attack speed, and damage. (any leftovers go to range/mana) and finally for mage upgrade attack speed mana and attack. (leftovers range)
Nice strategy, i used attack speed and damage on knight, i used rage, and every 0.3 seconds, happens a attack of 140+. Same for archer, when use the focus skill, fires one arrow after another.
I'm going to wager there are already threads and guides that have more discussions and replies over here and here. So post there, since gamers congregate there.