Main Article: Buildings
- All buildings, except for tier 1 towers and shrines have this ability (although tier 1 towers have the 60% damage reduction against illusions).
- Tier 2 towers have a search radius of 900 centered on them, each of them independent from each other.
- The base buildings depend on the Ancient's search radius of 4000 centered on it. This means they all lose the protection together.
- The unit detection is aura-based. If an enemy lane creep gets within the search radius of the tower/ancient the protection is lost.
- The aura's effect lingers for 0.5 seconds, so the total reactivation delay is effectively 15.5 seconds.
- While protected, the building takes 40% less damage from any source, and 75% less damage from illusions.
- This includes spell damage, not only attacks, including spells cast by illusions.
- While unprotected, the building only takes 60% less damage from illusion attacks (excluding their spells).
- If a backdoor-protected building is damaged by an enemy, it immediately starts healing back.
- Heals 9 health in 0.1 second intervals, which translates to 90 health per second.
- This means, it is possible to destroy protected buildings by dealing more than 90 damage per second (after reductions).
- Only heals back damage dealt by enemy units. Damaged dealt by allies is not healed back.