Strikethrough

While wielding a Two-Handed Weapon, or while wielding a Bastard Sword or Dwarven Axe in your main hand and a Shield, Orb, Rune Arm, or nothing in your offhand, your attacks can Strikethrough. When your attacks can Strikethrough, every attack has a chance ("Strikethrough Chance") to hit an additional target. By default, players have a 20% Strikethrough Chance (which can be improved through feats and enhancements). If your Strikethrough Chance is over 100%, you are guaranteed to hit a second target (if in range) on your attacks, with a chance to hit a third.

Strikethrough was introduced in Update 45 and replaced Glancing blows.

Improving strikethrough chance
TBD
 * Feats

TBD
 * Enhancements

TBD
 * Epic abilities

TBD
 * Items

Special attacks that strike through
Some special attacks are able to hit the secondary target(s). Based on.

Barbarian

 * Cracking Attack (FB)

Bard

 * Frozen Fury (Warchanter)

Cleric

 * Warpriest Smite

Druid

 * Nature's defensive stance allows strikethrough. While in bear form strikethrough works regardless of what weapons you wield.

Favored Soul

 * War Soul Smite

Fighter

 * Kensai enhancement - Shattering Strike

Monk

 * Finishing moves
 * Fire/air/water/earth strikes
 * Enhancement - Ninjutsu line (modify touch of despair finishers)
 * Enhancement - Elemental words (all-consuming flame, porous soul, static charge, winters touch)

Paladin

 * Smite evil

Feats

 * Stunning Blow
 * Trip

Epic abilities

 * DC - Smite the wicked
 * FoTW - Boulder's Might
 * LD - Lighting mace, volcano's edge. I didn't test Anvil of thunder but I assume it works to.
 * SD - Executioners strike
 * US - Celestial Mandate (Couldn't test hate effect)
 * US - Draw them out (Couldn't test hate effect)

Special attacks that don't strike through
TBD