Damage can be blocked in 3 ways:

1.

Stout Shield: 40% chance to block 30 damage. (equivalent to 12 damage block on all attacks).

2.

Vanguard: 65% chance to block 40 damage. (equivalent to 26 damage block on all attacks).

3.

Kraken Shell

(Tidehunter): 100% chance to block 7/14/21/28 damage.

Now for the mechanics:

- Damage block comes before armor reductions and reduces physical attacks.

Explanation:

If a unit with 1 Stout Shield and 5 armor (equal to 23% damage reduction) takes a 70 damage attack then:

A. The unit has a 40% chance to take 31 damage - Stout Shield takes effect ((70 - 30) * (1 - 0.23))

B. The unit has a 60% chance to take 54 damage - Stout Shield does not take effect (70 * (1 - 0.23))

- If you have more than one damage block source,they are individually checked in reverse order of acquisition, and only one can trigger.

Explanation:

That is, let us suppose you have a stout and a vanguard in your inventory. You drop your stout and pick it up again. Then the last acquired item is stout.Now when attacked, the stout is checked first, then the vanguard. If the stout's block succeeds, then the Vanguard will not be checked anymore. This is highly unwanted and it should be made a point not to make this mistake.

- Here is a list of some scenarios:

2 Stout Shields => 64% chance to take 30 less damage & 36% chance to take normal damage. [Note that you do not get a chance to take 60 less damage, since only one source will ever trigger]

2 Vanguards => 87.75% chance to take 40 less damage & 12.25% chance to take normal damage. This is why 2 vanguards is not a good investment. You pay 2275G for 22.75% chance to block 40 damage (+extra benefits of vanguard).

1 Stout Shield then 1 Vanguard [Ideal Scenario]=> 65% chance to take 40 less damage, 14% chance to take 30 less damage, 21% chance to take normal damage.

1 Vanguard then 1 Stout Shield [Unwanted Scenario] => 40% chance to take 30 less damage, 39% chance to take 40 less damage, 21% chance to take normal damage.

- The rules apply similarly for Kraken Shell(Tidehunter). If you bought a Stout Shield THEN learned 1 level of Kraken Shell, your Stout Shield will never be used. Kraken Shell was acquired last and is thus checked first, but since it always goes off, the Stout Shield never has a chance to kick in.