Doublestrike

Doublestrike
Doublestrike grants a character a chance to make an additional attack roll with their main hand weapon any time they make a main hand melee attack. The additional roll is made on the target of the initial attack. Doublestrike only applies to melee attacks.

Doublestrike was introduced as part of the Update 5 combat changes. Many attack speed bonuses were converted to Doublestrike effects at that time.

Morale bonus
Most bonuses from equipment and songs are Morale bonuses and do not stack with each other - only the highest will apply.
 * The Bard Warchanter II song Inspire Recklessness grants a +5% Morale bonus to Doublestrike and -10% fortification to all nearby allies.
 * 3% items:
 * As a prefix on lootgen Gloves and Rings.
 * Category:Doublestrike items/3%
 * 6% items:
 * As a prefix on lootgen Gloves and Rings.
 * Alchemical Crafting Tier 2 Martial Air effect includes a +6% bonus to Doublestrike.
 * Category:Doublestrike items/6%
 * Medusa Fury - this effect on a few weapons grants a +5% bonus to Doublestrike when the wielder is below 25% hitpoints.

Enhancement bonus
Only the highest enhancement bonus to Doublestrike applies.
 * The Ranger Tempest III enhancement grants a +5% enhancement bonus to Doublestrike while wielding two weapons.
 * Monk Wind Stances grant a +2.5%/+5%/+7.5%/+10% enhancement bonus to Doublestrike.
 * The activated Druid Celerity enhancement grants a +50% enhancement bonus to Doublestrike for 15 seconds with a cooldown of 5 minutes.
 * The Legendary Dreadnought Tier 4 ability Lightning Mace grants a +15% enhancement bonus to Doublestrike for 6 seconds when you crit with a Club, Greatclub, Heavy Mace, Light Mace, Morningstar, or Quarterstaff in your main hand.

Shield-related bonuses
Bonuses in this section stack.
 * The Shield Mastery / Improved Shield Mastery feats grant a +3% / +8% bonus to doublestrike while wearing a shield.
 * The Unyielding Sentinel Tier 2 ability Legendary Shield Mastery grants a +[2/4/7]% bonus to Doublestrike while wearing a shield.

Other typed bonuses

 * Alchemical bonus - Cannith Combat Infusion on Fabricator's Bracers grants a temporary 5% alchemical bonus to Doublestrike.
 * Artifact bonus - The Draconic Ferocity set bonus on Flawless Black Dragon Armor/Helm of the Black Dragon grants a +3% artifact bonus to Doublestrike.
 * Competence bonus - The Fighter Weapon Alacrity fighter capstone includes a +10% competence bonus to Doublestrike.
 * Profane bonus - The Shadowdancer innate ability Shadow Training IV grants a +3% profane bonus to Doublestrike while wielding weapons that qualify for Weapon Finesse.
 * Sacred bonus - The Paladin spell Zeal grants a +10% Sacred bonus to Doublestrike to the caster.

Untyped
Untyped bonuses stack.
 * Opportunist, a Rogue Special Ability feat, grants a +3% bonus to Doublestrike.
 * The Natural Fighting Druid feat grants a +6% bonus to Doublestrike when in animal/magical beast form; and can be taken up to 3 times.
 * The Grandmaster of Flowers Tier 2 ability Running with Wind grants +[1/2/3]% to Doublestrike if you are in Monk Wind Stance.
 * The Grandmaster of Flowers Tier 2 ability Hail of Blows grants +3% to Doublestrike.