Unique Attack Modifier

Orb effects in Dota 2 refer to attack modifiers that alter your heroes basic attack to provide an additional effect. An example of this is Helm of the Dominator, which gives your hero lifesteal. For balance and legacy reasons, orb effects, with very rare exceptions, do not stack. Having more than one at any time is generally considered useless. Certain hero abilities, such as Broodmother's Incapacitating Bite, also count as orb effects. Not all attack modifiers count as orbs.

When two orb effects are acquired by one hero, the last one acquired usually takes priority. For skills, activation of active orbs counts as acquiring. Otherwise, it was when the skill was first leveled up.

All items in the Artifacts shop, with the notable exception of Yasha, grant orb effects.

List of items that grant Orb Effects

 * [[Image:Helm_of_the_Dominator.png|Helm of the Dominator|40px|link=Helm of the Dominator]] Helm of the Dominator
 * [[Image:Mask_of_Madness.png‎|Mask of Madness|40px|link=Mask of Madness]] Mask of Madness
 * [[Image:Sange.png‎|Sange|40px|link=Sange]] Sange
 * [[Image:Maelstrom.png‎|Maelstrom|40px|link=Maelstrom]] Maelstrom
 * [[Image:Diffusal_Blade.png‎|Diffusal Blade|40px|link=Diffusal Blade]] Diffusal Blade
 * [[Image:Desolator.png|Desolator|40px|link=Desolator]] Desolator
 * [[Image:Sange_and_Yasha.png‎|Sange and Yasha|40px|link=Sange and Yasha]] Sange and Yasha
 * [[Image:Mjollnir.png‎|Mjollnir|40px|link=Mjollnir]] Mjollnir
 * [[Image:Skadi.png‎|Eye of Skadi|40px|link=Eye of Skadi]] Eye of Skadi
 * [[Image:Satanic.png‎|Satanic|40px|link=Satanic]] Satanic

List of hero skills that count as Orb Effects

 * [[Image:Mana_Break_icon.png|Mana Break|40px|link=Anti-Mage#Mana_Break]] Anti Mage's Mana Break
 * [[Image:Frost_Arrows_icon.png|Frost Arros|40px|link=Drow_Ranger#Frost_Arrows]] Drow Ranger's Frost Arrows
 * [[Image:Impetus_icon.png|Impetus|40px|link=Enchantress#Impetus]] Enchantress's Impetus
 * [[Image:Caustic_Finale_icon.png|Caustic Finale|40px|link=Sand_King#Caustic_Finale]] Sand King's Caustic Finale
 * [[Image:Incapacitating_Bite_icon.png|Incapacitating Bite|40px|link=Broodmother#Incapacitating_Bite]] Broodmother's Incapacitating Bite
 * [[Image:Poison_Sting_icon.png|Poison Sting|40px|link=Venomancer#Poison_Sting]] Venomancer's Poison Sting
 * [[Image:Poison_Attack_icon.png|Poison Attack|40px|link=Viper#Poison_Attack]] Viper's Poison Attack
 * [[Image:Geminate_Attack_icon.png|Geminate Attack|40px|link=Weaver#Geminate_Attack]] Weaver's Geminate Attack

Buff Placers
Many orb effects also count as Buff Placers. Buff Placers follow the same rules as Orb Effects, but count separately. Buff placers usually apply a "buff" (actually a debuff) to the target, and can be carried by an orb effect. For example, Desolator grants the Corruption Orb Effect attack modifier, which applies the Corruption (-6 Armor) debuff to the target.

Buff placers that are not Orb Effects will stack with Orb Effects, but not with each other. For example, Lifesteal from Helm of the Dominator will stack with Orb of Venom, which is a Buff Placer only, but not with Desolator or Maelstrom, which both contain Orb Effects.