Buildings

Buildings are a type unit that are not controlled by any player. At the beginning of each match, a set of buildings spawn at set locations for both teams. Both factions have the same set of buildings, with only their appearance differing from each other. Buildings take mostly defensive roles and are the main objective of the game.

All buildings have the same base properties. They are immune to most spells (with only a few spells affecting them), have the structure armor type, deal siege damage if they can attack and are immobile. When destroyed, some buildings grant gold to the entire enemy team, while others grant gold only to whoever made the last hit. Once below 10% health, buildings (except for the Ancients) can be denied to prevent the enemy from getting their gold bounties, or to reduce the amount they get. Buildings do not grant experience. Once destroyed, a building is permanently lost, as they do not respawn.

There are a total of 29 buildings on each side.

Towers
Towers are the main line of defense for both teams, attacking any non-neutral enemy that gets within their range. Both factions have all three lanes guarded by three towers each. Additionally, each faction's Ancient has two towers as well, resulting in a total of 11 towers per faction. Towers come in 4 different tiers:
 * Tier 1 towers, located at the end of each lane.
 * Tier 2 towers, located halfway through each lane.
 * Tier 3 towers, located on top of the 3 ramps at each base.
 * Tier 4 towers, located in pairs in front of each Ancient.

Tier 1 towers are invulnerable during the preparation phase, until the battle begins. Each Tier 2 and tier 3 tower is invulnerable until the lower tier tower preceding it in its lane is destroyed. The two tier 4 towers are invulnerable until any of the tier 3 towers have been destroyed. Barracks do not have to be destroyed to make tier 4 towers vulnerable. Both of the tier 4 towers must be destroyed in order to remove the Ancient's invulnerability.

All towers have a vision range of during the day. Tier 1 towers have a night vision of, while higher tier towers have a night vision range of. Additionally, all towers have True Sight in a area around them, and have one defensive and one supportive ability. Towers can attack, but never attack nearby neutral creeps.

Towers grant a gold bounty to whoever makes the last hit, but also grant a team bounty to the entire team. When denied, both team get half the team bounty.

Attack Priority
Towers are using regular auto-attacking, so when multiple enemies engage the tower, it naturally targets the first enemy that gets within its attack range. It sticks with that target until it can no longer be attacked (it dies, gets out of attack range or becomes attack immune). Once that happens, it chooses the next attack target using the following priority system.
 * 1) Closest enemy unit attacking the tower itself
 * 2) Closest enemy unit attacking an ally of the tower
 * 3) Closest enemy unit

It does not matter whether the unit is a hero or a non-hero unit, they are treated equally. Units treated differently are wards and siege creeps. These units are always attacked as last. If a tower attacks one of these units, and then another unit or hero come within range, the tower immediately switches to the new unit. Siege creeps have a higher priority than wards.

There are two additional scenarios where the tower switches its attack target immediately:


 * 1) If an enemy hero attacks an allied hero while within 500 range of the tower, it immediately switches to that enemy hero. This only works against enemy heroes. Non-hero units attacking heroes do not cause the tower to switch aggro towards them. The attack does not have to finish or connect, the attack order alone is enough. However, it has to be a regular attack, instant attacks or manually casting an active attack modifier do not count. This behavior is akin to lane creeps' behavior, which do the same in this scenario.
 * 2) On the other side, if the currently targeted enemy unit (hero or non-hero alike) is ordered to attack its own allies (hero or non-hero alike), the tower immediately switches aggro to another unit, using the priority system mentioned above. This as well does not require the attack to start, the order alone is enough. Enemies can de-aggro the tower only once every 2.5 seconds by using this technique. This behavior is also equal to that of lane creeps. If the tower has already started its attack on a unit, it will finish that attack, even when aggroed or de-aggroed with these techniques. This means it is impossible to cancel the tower's attacks by changing its aggro. Its attacks only cancel when its current target cannot be attacked anymore.

Barracks


Barracks (commonly shortened to Rax or Racks) are buildings, defended by their 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 (called Melee Barracks or Melee Rax), and one for ranged creeps (called Ranged Barracks or Ranged Rax). The ranged barracks are always located to the left of the melee barracks on each lane and both factions.

Barracks are invulnerable until the tier 3 tower guarding them is destroyed. The loss of barracks does not stop lane creeps from spawning. However, destroying Barracks grants the destroying team super creeps in that lane, corresponding to which one was destroyed, which are more powerful and grant less bounties than regular creeps. Super melee creeps spawn when the melee barracks get destroyed, while super ranged creeps spawn when the ranged barracks are destroyed. When all 6 Barracks of a team are destroyed, mega creeps start spawning on every lane for the enemy, even more powerful than super creeps.

All barracks have a vision range of during the day and  during the night. They cannot attack, have no special abilities and have no True Sight.

Barracks grant a gold bounty to whoever makes the last hit, but also grant a team bounty to the entire team. Denying Barracks does not reduce the team bounty.

Ancients
Ancients (also commonly refered to as Thrones, or Tree for Radiant's ancient and Throne for Dire's ancient, as legacy names from DotA) are massive structures found inside each faction's base and are the main objective. In order to win, the enemy team's Ancient must be destroyed, while the own one must be kept alive. Ancients are guarded by their two tier 4 towers. The Ancients are invulnerable until both of their tier 4 towers are destroyed.

Both ancients have a vision range of during the day and  during the night. Additionally, they have True Sight in a area around them.

Fountains
Fountains are buildings located in the respawn areas of both bases, and provide scaling health and mana regeneration to all allied units near it. They also greatly defend the spawn area, blasting intruding enemies with very rapid high-damaging attacks, which grow stronger with each blow, have 25% accuracy, dispel consumables, and disable Blink Dagger, Heart of Tarrasque and other abilities that are normally disabled by player-based damage. Fountains use the same attack priority system as towers, except that they cannot be aggroed immediately by attacking an enemy hero. Fountains are permanently invulnerable, so they can never be destroyed.

Both fountains have a vision range of during the day and  during the night and can attack. Additionally, they have True Sight in a area around them.

Effigy Buildings
In addition to the above buildings, there are other buildings that act as buffers within a base, called Effigy Buildings, or Filler Buildings (although they are just named Building in-game). These buildings exist only to occupy enemy creeps before reaching the tier 4 towers or the Ancient, and therefore give the defending players more time to act. There are 7 such buildings in each base, spread evenly around the Ancient.

Five of the seven Effigy buildings (the 5 forming a half-circle around the Ancient) are customizable with Effigy Blocks, giving them a different look and making them display a text notification when destroyed. This has purely cosmetical values and does not alter them in other ways. Each player can customize one of the five Effigy Buildings in their base.

All effigy buildings have a vision range of during the day and  during the night. They cannot attack, have no special abilities and have no True Sight.

Radiant's buildings have two different models, while the Dire have one model for all.

Outposts
Outposts are buildings located within the primary jungles of both teams, close to the small neutral creep camps on the highground - West from the camp in the Radiant jungle and East from the camp in the Dire jungle. Outposts start out belonging to the team on their side, and can be captured by the enemy after destroying a tier 2 tower. Taking back a stolen outpost can be done without having to destroy an enemy tier 2 tower.

Outposts have a ground vision range of during the day and  during the night. Additionally, they have True Sight in a area around them. The vision and True Sight are only granted to the controlling team. Holding ALT displays the vision range, regardless of which team the outpost belongs to. The outposts are always visible through the fog of war, no matter whom they belong to, so capturing them can be easily noticed by the other team, as its animations are visible, and the sound is audible. When under control, outposts can be teleported to with and, although with a lower teleport radius and a longer channeling time. Losing control of an outpost while channeling a teleport does not cancel the channeling.

Although attackable by non-hero units, and targetable by spells that affect buildings, outposts cannot be damaged at all, so they are undestroyable.

Backdoor Protection
Backdoor Protection is a passive ability almost all buildings have. Tier 1 towers, Outposts and Fountains are the only buildings without this ability. While active, Backdoor Protection grants high damage resistance to the building, and causes it to heal back any damage it takes from enemy units, making them difficult to destroy. This protection deactivates when an enemy lane creep moves within range of the building (if it is a tower outside the base), or gets close to the team's base (if it is a building within the base). The creep must not be dominated by a player, only AI-controlled lane creeps can deactivate the protection. Once deactivated, it takes some time for the protection to activate again.

There are 4 separate disable areas of Backdoor protection. Each tier 2 tower has its own circular area centered on them, providing protection to themselves, and the ancient has a gigantic circular area centered on it, providing protection to all buildings inside the base (except the fountain). This means each of the tier 2 towers have independent protections, meaning when one is disabled, the others are not disabled. They are also independent from the base protection. Meanwhile, all buildings inside the base share one protection and lose it simultaneously when disabled. The radius of the Ancient's disable area is so huge that it goes beyond the elevated base area. On the Dire side, it reaches up until halfway between the top tier 2 tower and the top base ramp, up to the mid tier 2 tower and up until just shy of the ward spot next to the bottom tier 2 tower. On the Radiant side, it reaches behind the top tier 2 tower, beyond the mid tier 2 tower and halfway between the bottom tier 2 tower and the bottom base ramp.

Backdoor protection is not responsible for the invulnerability buildings have, so the buildings still stay invulnerable if their corresponding towers are not destroyed first.

True Sight
Towers, Ancients and fountains, all have True Sight, the ability to detect nearby invisible enemy units. The radius' are different for between them.

Glyph of Fortification
The Glyph of Fortification (or Glyph in short) is an ability usable by any player that causes all friendly buildings and lane creeps to become impervious to damage for a short duration, while also granting tier 2 and higher towers a multishot attack, allowing them to attack multiple enemies at the same time. The effect has a rather low duration and very high cooldown, making the timing of usage very important. The Glyph is used strategically to stop enemy pushes or slow them down long enough to organize a defense. It may also be used offensively to secure a push by granting the creep waves damage immunity at the right time, or even for finishing enemies off by using the multishot attacks.

The Glyph of Fortification can be activated by any player with a button at the right of the minimap or the shortcut they defined in the settings. The Glyph's cooldown is shared by the entire team, meaning if one player uses it, it goes on cooldown for all players of the team. However, whenever a tier 1 tower falls, the Glyph's cooldown gets refreshed 1 second later.

Glyph Trivia

 * In DotA, Glyph grants friendly buildings spell immunity and +9999 armor, instead of 100% damage resistance like in Dota 2.
 * This means physical attacks still did 1 damage to them, since 100% physical damage resistance cannot be achieved with just armor, and the game rounds damage numbers to full numbers.
 * This also means that fortified buildings cannot be targeted by some spells which otherwise could target them.
 * In earlier versions of DotA, Glyph did not grant spell immunity, and skills such as 's could deal damage through it.

Abilities Affecting 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 structure armor as well as standard armor value reductions.