Armor & Damage Reduction

Alot people forget about upgrading their armor in dota. They usually buy damage item because they want to kill the opponent as fast as possible. Armor give you more survivability compare to damage item in battle.

Each increase in armor increases your effective HP by 6%. This means that having 1000 HP with 10 armor is equal to 1000 + (1000 * 0.06 *10) = 1600 effective HP. If you have 17 armor, your effective HP is double.

Armor will reduce the physical damage from your opponent. The formula to know the reduction of physical damage is 1 - ( 1/ (1 + (armor * 0.06)))


What is the best amount of armor should i get? Usually the more armor you have, the better. But as you can see from the chart, the most effective armor is 17. However, it is better to have 23-27 armor for end game because your opponent will obtain desolator or assault cuirass which will reduce your armor.

early game - 7 to 9 armor
mid game - 17 armor
end game - 23 to 27 armor

Vanguard, armor , kraken shell relationship
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How do you calculate damage if you have kraken shell, a stout shield , a vanguard and armor?

This is the sequence for calculating reduce damage
1) stout shield or vanguard
- which last item you pick up or create will block the damage first. So if you have stout shield and vanguard in your item list, put down vanguard and pick it up again. Make it your primary reduce damage item.

2) kraken shell
- if stout shield or vanguard could not protect you, then kraken shell will block the damage. However, if stout shield or vanguard block the damage, then kraken shell will not reduce the damage.

3) armor
- After blocking the damage from both above, the armor reduction is calculated.

One thing to notice is that vanguard could only block about 18 to 30 damage. If creep attack you below 40 damage, you will not received any damage. Early game to mid game, vanguard is very useful because you can dive in to the tower or creep and kill hero. It is useless end game when your enemy have 200+ damage.

What item can help increase your armor
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1) Plate Mail = +10 armor
2) Chain Mail = +5 armor
3) Helm of Iron Will = +5 armor
4) Ring of Protection = +2 armor
5) get item that increase agility (7 agility = 1 armor)