Each hero has four attributes. While all Castellans require Int, combat heroes may emphasize different attributes, based on your strategy. The details are given below.
Attack
This increases the damage of your units. Attack is very useful for any hero; in particular if the enemy have a high defense you may find yourself doing comparatively little damage if your Attack doesn't compensate.
Attack multiplies the damage your unit will do by 1+ATK/100.
Defense
Strengthens the defense of your troops, meaning they take less damage. With sufficient defense an enemy attack can even do no damage at all. If you neglect hero defense totally you are going to take plenty of damage when fighting other players. However if you are working on a first-strike strategy when fighting against NPCs you probably don't need defense.
Divides the damage a unit would take by 1+DEF/100.
Speed
Higher hero speed increases unit speed. Unit speed affects both the movement rate on the map as well as the order of actions in combat. Having missile troops with high speed being able to hit the opponent first means you can destroy the enemy without taking any damage.
The amount of speed increase is equal to (Hero Speed - 10)x0.02. This is added to the speed of each unit.
Intelligence
While all of the previous attributes are for combat heroes, Intelligence is only for Castellans. It increases the gold production in the castle that the Castellan rules. The end effect is 2 extra gold per hour, but it does add up as the days go past. Intelligence doesn't affect the production of other resources, not does it seem to affect anything else in the game. Hence combat heroes normally ignore Intelligence totally.
