Stack

[OrNy]

Evasion , Block , Crit . They can stack ? I mean Mortred with a Buriza . Axe wth 2 Vanguards . Mort with a Butterfly .

[reddragon137]

no

[SoletLuna]

Originally Posted by reddragon137

no

lol.

Originally Posted by OrNy

Evasion , Block , Crit . They can stack ? I mean Mortred with a Buriza . Axe wth 2 Vanguards . Mort with a Butterfly .

Evasion: Highest value.
Damage Block: Checked in reverse order of acquisition, successful proc ends the check.
Crit: Last acquired only, if multiple proc on the same attack.

[Fire525]

Probably mentioning that miss and evasion stack diminishingly.

[JohnnyMoe]

Item's Passive Skills Stacking Guide - DotA Mechanics

[Pingus!]

Damage block

Case 1: Similar items

2 Vanguards

The last acquired Vanguard has its chance to block processed first, and if it fails to block then the second Vanguard takes effect. Thus the chance to block is:

0.7 + (1 - 0.7) * 0.7 = 0.91

2 Vanguards thus provide a 91% chance to block 40 damage. As you can see, the second Vanguard only increases the block chance by 21%, and a third would increase it by 4.9%, thus stacking multiple Vanguards results in diminishing returns to cost.
[edit] Case 2: Different Items

Vanguard + Stout Shield, Vanguard acquired last.

Since the Vanguard was acquired after Stout Shield, the chance for it to block is processed first. Only if it fails to block will Stout Shield's chance be processsed afterwards, if the 70% chance is met then Stout Shield is completely overridden.

Thus the chance to block is:

0.7 + (1 - 0.7) * 0.6 = 0.88

Of this 88% chance to block, 70% of the time Vanguard blocks, 18% is Stout Shield blocking. Since they are calculated in reverse order, it would be advisable to acquire your largest source of Damage Block last (simple, just drop and pick it up) so it will override all others. If we had placed Stout Shield last the total chance would still be the same, but 60% of the time Stout Shield would block, and only 28% for Vanguard.Since Vanguard blocks more damage, it is preferable to have it override.

Evasion

If a unit has two or more abilities or items that grant evasion, only the ability with the highest percent to evade an attack will be used.

[krunyul]

Evasion and Miss