Crushing Blow

For ranged attackers like the bowazon, Crushing Blow (CB) erases 1/8 a monster's actual life in Single Player mode. This fraction is unaffected by hit point modifiers in multiplayer games. What is significant to note is that crushing blow is applied before all other types of damage, so when you hit, there is a chance you erase 1/8 the target's actual single player life, regardless of the damage inflicted by the weapon, then apply damage in the normal order. For a ranged attacker, the damage inflicted by crushing blow would be:

100/(2 × (players in game + 1)) ÷ 2 = percentage life loss of actual life.

Against champions, uniques, super uniques, and act bosses, this is lowered to 1/16 their base life. Against objects like lightning spires and doors, CB erases 1/10 of their hit points. Hostile players and hirelings have the lowest percentage, at only 1/20 their base life.

Crushing blow items are additive. There is no limit to how many CB items you can use, so it's possible to have 100% crushing blow, meaning that every succesful hit will inflict CB.

According to Tommi Gustafsson, CB isn't damage, so is unaffected by damage modification effects like Bone Armor or Energy Shield. However, crushing blow is affected by positive physical resistance, so physical immune monsters are unaffected by CB. Negative physical resistance, on the other hand, has no effect on Crushing Blow's effectiveness. Hence, a target under the effect of Amplify Damage won't take double damage from a CB.

Where can I get crushing blow?

Equipment:

Duress (Shael + Um + Thul) rune word armor (15%)

Goblin Toe light plated boots (25%)

Gore Rider war boots (15%)

Guillaume's Face winged helm (35%)

Horadric Blood gloves [magic heavy/sharkskin gloves/vampirebone gloves + Nef rune + perfect ruby + magic jewel] (5-10%)

Rattlecage gothic armor (25%)

Venom Grip demonhide gloves (5%)

Sockets:

Ber rune (20%), when socketed in weapon