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.

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 (Melee only. Ranged is Buff Placer only)
 * [[Image:Satanic.png‎|Satanic|40px|link=Satanic]] Satanic

List of hero skills that grant 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_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.

The following is a list of Buff Placers that are not Orb Effects:


 * [[Image:Poison_Sting_icon.png|Poison Sting|40px|link=Venomancer#Poison_Sting]] Venomancer's Poison Sting
 * [[Image:Orb_of_Venom.png|Orb of Venom|40px|link=Orb_of_Venom]] Orb of Venom
 * [[Image:Skadi.png‎|Eye of Skadi|40px|link=Eye of Skadi]] Eye of Skadi (only on ranged heroes)

Critical Strike and Bash
Critical Strike also counts as a Buff Placer for ranged heroes, on the attack in which it procs. Crystalys and Daedalus both grant Critical Strike. Monkey King Bar's True Strike ability also counts as a Critical Strike, but will not interfere with other Critical Strikes.

Bash likewise counts as a Buff Placer for ranged heroes on attacks in which it procs. Bash may be gained from Skull Basher.

Stacking
Since Orb Effects modify attacks, two orbs will not stack. Orb Effects that are also Buff Placers can stack with other Buff Placers. Maelstrom, for example, is always an Orb Effect, but has a 25% chance to proc Chain Lightning, which counts as a Buff Placer. If a hero possesses another Buff Placer (from, for example, Orb of Venom) the other Buff Placer will apply every time Maelstrom does not, and Maelstrom will apply when it procs (overriding any other Buff Placers). In practice, this means a hero may possess two Buff Placers, provided that one is probability based. This also applies to both Critical Strikes and Bashes. Only one may proc at a time for ranged units, but both will work (and in fact will work with other Buff Placers).

Activated skills that are Orb Effects will override any other orbs, except for Lifesteal. Lifesteal will only be overridden if the Orb Effect is placed on autocast, but not for single casts. In practice, this means that heroes such as Drow Ranger who wish to use a second Orb Effect may do so, but not simultaneously and only by using autocast.

Quelling Blade is not technically either an Orb Effect or a Buff Placer, but it will not work if the hero possesses either an Orb Effect or Buff Placer, except Skadi in its ranged form. It will work with probability based Buff Placers whenever they do not proc.