Buildings

Buildings are special units that are immune to most spells, use Fortified Armor, and are immobile. Destroying a Building rewards you with a bounty, similar to most Creeps or Heroes. However, some Buildings will also give a bounty to the entire team, rather than the destroying player. Buildings are divided into several categories, each with their own role.

Towers
Each faction's three lanes are guarded by 3 Towers, and their Ancient guarded by 2 neighboring Towers. Towers become higher tier depending on how far they are in a lane. Every Tower, except for Tier 1 Towers, is invulnerable until the Tower proceeding it is destroyed. The two Towers defending a team's Ancient become vulnerable if any Tier 3 Tower is destroyed. Note: No barracks have to be killed to make these towers vulnerable. Both of the Tier 4 Towers must be destroyed in order to remove the Ancient's invulnerability.

All towers have a sight range of 1800/800, and an attack range of 700. All Towers deal Siege Damage, which deals only 75% damage to Heroes, but 150% damage to all siege Lane Creeps. Additionally, all towers have True Sight in a 900 area around them, allowing them to see any invisible units including Observer Wards and Sentry Wards.

Towers can be denied, just like creeps, once they have 10% health or less. This means that tier 1 towers (1300 total HP) can be denied at 130 health or lower, and tier 2-4 towers (1600 total HP) can be denied at 160 health or lower. Denying towers reduces the gold and experience bounty gained by the enemy team.

Towers have a specific targeting priority that determines which enemy it will attack. This list represents that priority in ascending order:
 * 1) Closest enemy unit or hero attacking a friendly hero with auto attack
 * 2) Closest enemy unit or hero attacking the tower itself with auto attack
 * 3) Closest enemy unit or hero attacking any friendly unit with auto attack
 * 4) Closest enemy unit
 * 5) Closest enemy hero
 * 6) Closest enemy catapult

The tower will only switch targets under three circumstances:
 * If the targeted enemy unit or hero dies
 * If an enemy unit or hero targets a friendly hero
 * If an enemy hero being attacked by the tower manually attacks a friendly unit or hero (in which case, the tower will select a new target based on the above priority order).

When an enemy tower is destroyed, all allied heroes receive the tower's bounty as reliable gold.

If a hero gets the last hit on a tower, he receives an additional 150-250 unreliable gold.

If a tower is denied, the bounty is much lower.

Ancients
Ancients are massive structures found inside each faction's base. In order to win, each team must destroy the enemy team's Ancient. Ancients have no offensive abilities themselves, but are guarded by 2 Towers. They cannot be attacked until both Towers are destroyed.

Ancients have 4250 hit points, and regenerate 3 hit points/second. Ancients also have 15 armor, 1800/1800 sight range, and True Sight in a 900 area around them.

Barracks
Barracks are special buildings, defended by Tier 3 Towers, that are responsible for keeping Lane Creeps as powerful as their counterparts. There are two Barracks for each lane per faction - one for Melee Creeps, and one for Ranged Creeps. Destroying either Barracks provides a large boost to the destroying team's associated Lane Creeps, increasing their statistics, as well as reducing the gold and experience they give when killed.

Barracks are invulnerable until the Tower that is guarding them is destroyed. Melee Barracks have 1500 hit points, and regenerate 5.0 hit points/second while Range Barracks only have 1200 hit points and 0.0 hitpoints/second regeneration. Barracks also have 900/600 sight range and a bounty of 352-370 gold. This bounty is only given to the hero that gets the last hit. Barracks do not have True Sight, but do have backdoor protection. Radiant and Dire Melee and Range Barracks

Fountains
Fountains are Buildings located in the respawn areas of both bases, and provide healing and mana regeneration to all allied units near it. They also attack any enemy unit that comes within 800 range, dealing 190-199 physical chaos damage per attack. Fountains have a True Sight radius of 900(not accurate). They are also invulnerable for balancing reasons.

Mana and Health regeneration provided by the fountains is 4% maximum HP or Mana per second plus an additional 14 Mana points per second. It takes about 25 seconds to heal any hero from low health to full. Dropping items that provide Mana speeds up the process.

Bottles that are not full will be automatically refilled when you are near the fountain. Using Bottles while near the fountain speeds up the rate of regeneration, allowing Heroes to heal themselves and restore Mana faster.

Subsidiary Buildings
In addition to the above Buildings, there are other Buildings that act as buffers within a base. These Buildings have no effect on a team's outcome, other than providing a buffer for Lane Creeps to attack once they are inside of a base, and dropping a larger than normal gold bounty when destroyed.

Other Buildings have 500 health, 0 armor (fortified), and backdoor protection.

Gold if last hit: 102-120

Backdoor Protection
All buildings except for the Tier 1 Towers possess the passive ability backdoor protection. Backdoor protection activates when there are no nearby enemy creeps, and causes the building to take 25% damage from illusions and 75% damage from other units. If a backdoor-protected building is damaged by an enemy, it will regenerate the lost health at a rate of 90 HP per second. It is still possible to destroy protected buildings with sufficiently high damage. Backdoor protection will not regenerate damage dealt by friendly units.

On the Tier 2 Towers, backdoor protection is independent for each tower. The faction base applies backdoor protection as one single unit, e.g. if there are enemy creeps near one Tier 3 Tower, all the other Tier 3 towers and barracks will drop their backdoor protection as well.

Glyph of Fortification
The Glyph of Fortification is an ability usable by any player on a team that renders all buildings owned by their team invulnerable and magic immune for a short duration. It can only be used once every 5 minutes, and lasts for 5 seconds. The Glyph can be used to stop enemy pushes, or slow them down long enough to organize a defense.

Abilities that Affect Buildings
The following abilities can target or damage buildings.

Most hero abilities that deal physical damage are considered Hero damage and are reduced by 50% against Fortified armor as well as standard armor value reductions.

While under Glyph of Fortification buildings are magic immune and will interact with abilities as such. For example, Song of the Siren will not affect buildings under Glyph.