Armor Armor is extremely important, and most useful to one-man armies. With high armor you hero can resist ALOT arrow damage, which makes him useful for taking down archers and whole armies overall. Make this very high if you'r hero is a tank and or leadership hero.
Power Power is basically the amount of damage your hero can do with his initial melee attack. I only recommend this getting high for hero killers who need to bash out an extremely lot of damage in a short time. Don't waiste to much points to it otherwise.
Health Health determines the amount of health your hero has. This is needed especially for tanks, hero killers and leadership heroes. I think it is the second most useful stat, because a hero who is hard to kill always is a pain.
Health rate This is an extremely good stat to have high for any sort of hero, but mainly an archer and an hero killer. The archer needs to do hit and run attacks (which makes this extremely useful), and the hero killer who needs to have his health back ASAP (-> run away when you are damaged, and then return to fight when you are healed).
Vision This stat is only useful for the Archer and the Wizard, who need to have a good sight in order to perform their ranged attacks well. A spy could also have a good vision in order to, ofcourse, spy the enemy.
Thanks for waiting. I've done all the testing. You can find the results in this thread!
Ofcourse armor reduces damage, but by how much, and does it have some diminishig returns? And does it work against fireballs? Armor reduces damage depending upon the attribute points you give to it. Find how the armour changes with points in the above linked thread. Yes, it works against fireballs.
Does a hero with 10 points of power do exactly twice the damage of a hero with 5 points of power? A hero with 10 points of power does 150% of the damage that a hero with 5 points of armour does. Refer to tables provided, again in the above linked thread.
Does a slow-hitting Troll with 5 power do as much damage as a faster hero that also has 5 power? Yes. Apparently, they all hit at the same rate.
Does a hero with 10 points spent in health have double the HP of one with only 5? A hero with 10 points in health has 190% the original health, while a hero with 5 points in health has 140% the original. 5 point health = 2800 10 point health = 3800
How much HP does the regeneration points regenerate per second? It depends on the heal rate, but by my tests, the effects are only slightly improved with increasing points in heal rate. I observed that 2400 health was regained in 45 seconds for a hero with 5 points spent in heal rate.
Does increased Vision increase the range of archer-heroes? Yes, it does.