From the Arreat Summit:

*"Deadly Strike*

This is a chance of doing double damage. This bonus is applied after skills such as Critical Strike and any other damage bonuses. Critical Strike (CS) and Deadly Strike (DS) exclude each other.

If you have a 33% Deadly Strike item, and 68% Critical Strike Skill the complete chance to get double damage is:

=CS + (DS/100)*(100-CS)

=68% + (33/100)*32%

=68% + 10.56%

=78.56%

Open Wounds

This is a chance of making a monster bleed uncontrollably. They lose health while bleeding. Open Wounds Items stack in most cases.

Duration: 200 frames (that is 8 seconds).

The damage per frame seems to be the following (where Clvl is the attackers level, that is the player's level usually):

Clvl=1-15: (9*Clvl+31)/256

Clvl=16-30: (18*Clvl-104)/256

Clvl=31-45: (27*Clvl-374)/256

Clvl=46-60: (36*Clvl-779)/256

Clvl=61-99: (45*Clvl-1319)/256

If you prefer per second, just multiply by 25:

Clvl=1-15: 25*(9*Clvl+31)/256

Clvl=16-30: 25*(18*Clvl-104)/256

Clvl=31-45: 25*(27*Clvl-374)/256

Clvl=46-60: 25*(36*Clvl-779)/256

Clvl=61-99: 25*(45*Clvl-1319)/256

Some examples:

Clvl 10: 11.8 per sec over 8 seconds for a total of 94.5 damage. Clvl 30: 42.6 per sec over 8 seconds for a total of 340.6 damage. Clvl 50: 99.7 per sec over 8 seconds for a total of 797.7 damage. Clvl 70: 178.8 per sec over 8 seconds for a total of 1430.5 damage. Clvl 90: 266.7 per sec over 8 seconds for a total of 2133.6 damage.

Also, the damage is divided by 4 for a player target. In addition, for a missile versus a player target one should divide the damage by 8 instead.

Finally, versus bosses and champions (could be just bosses or special bosses) the damage is divided by 2.

Crushing Blow

This is a chance of reducing a monster's health by X% in a single blow.

-Default: 1/4th

-vs. Players: 1/10th

-vs. Hirelings: 1/10th

-vs. Champions, Uniques, Bosses: 1/8th

-with missile weapons, default: 1/8th

-with missile weapons, vs. Players: 1/20th

-with missile weapons, vs Hirelings: 1/20th

-with missile weapons, vs Champions, Uniques, Bosses: 1/16th

-The life removed is also scaled with number of players. So that if a monster has 450% more life due to 8 players (or whatever the value is) the life removed is further reduced by the same amount (450% would equal multiplying by 4.5 so the life removed by Crushing Blow is divided by 4.5).

Physical resistance does apply to Crushing Blow damage, but only if the resistance is positive. Crushing Blow Items stack in most cases. In 1.10 Crushing Blow is calculated before your normal damage. So, before doing the damage that you would normally do, there is a chance you will reduce the health of the monster by X% then normal damage apply to the resulting lower life. If you have more than one item with Crushing Blow, the probabilities will be added together. There will be one random check for a Crushing Blow. There is no check for each separate item, so one can not get multiple Crushing Blows in one attack."

So open wounds is like a physical poison, deadly strike is a critical hit (double damage), and crushing blow is like a physical static field (only applies to one target). They do not rule one another out (only critical strike/deadly strike). They stack, but there may be some caps (95% for deadly strike I heard).