Unique Attack Modifier
Unique Attack Modifiers (abbreviated UAM; formerly known as Orb Effects) are special attack modifiers that cannot be used simultaneously with each other—one always takes priority. They may be provided by abilities (e.g. Anti-Mage's Mana Break), or items (e.g. Morbid Mask).
Unique attack modifiers do work simultaneously with non-unique attack modifiers.
Multiple unique attack modifiers do not stack. One always takes priority, as follows:
- Unique active attack modifiers that were cast manually.
- Unique active attack modifiers set to auto-cast.
- Unique attack modifiers granted by items.
When attacking units that are immune to certain Unique Attack Modifiers (such as spell immune heroes or buildings) with an autocast modifier, other UAMs that it is vulnerable to will be used, even if they lower in priority. For example, Spell Immune heroes are immune to Arcane Orb, but if the hero is carrying a Morbid Mask, it will proc instead. This does not apply to non-autocastable UAMs like Mana Break—they still follow the above priority order regardless of a target's spell immunity.
Sources of Unique Attack Modifier