Mechanics

The Mechanics of Dota 2 describe the inner workings of the game. These are elements that are not required to play or even play well, but will improve a player's understanding of Dota 2 and provide them with more streamlined play. This article and the articles it links to describe more intricate elements of Dota 2 and are written for new and experienced players alike.

Engine


Dota 2 runs on a new version of the Source Engine. This version builds upon features introduced with Portal 2 and the Orange Box versions of the engine, such as flowmaps and advanced particle rendering, by adding features such as improved spectator support and cloth physics. Dota 2 supports a matchmaking system and up to 10 players in game at one time, but allows for large numbers of spectators in any given game.

Heroes
Heroes are all unique characters within Dota 2. At the start of each game, players are split into two teams of up to 5 versus 5 and then select a Hero from the Hero Pool. Every player controls his own Hero and any units that Hero controls, such as a Neutral Creep under the effects of Chen's Holy Persuasion or Lone Druid's Summon Spirit Bear.

Heroes will gain experience when enemy units are killed nearby. They start the game at level one, and as they earn experience, will eventually level up. Each level a Hero earns will increase their Attributes and learn new abilities.

Abilities
Abilities are the skills Heroes use to fight in the battlefield; they range from simple passive bonuses to powerful, devastating explosions. All Heroes have five or more abilities, with one of those abilities being their Ultimate, and another being their passive Attribute Bonus. Every time a Hero levels up, they earn a point that they can place into ranking up any available ability. Not all abilities will be able to have ranks placed in them at every level. The table at the right shows when ranks can be earned. For instance, heroes can't take a second rank of any regular ability until level 3, and can't take the first rank of their Ultimate until level 6. The exception is the Attribute Bonus, which can be taken at any level.

When an Ability is used, it will consume Mana and be placed on Cooldown. An Ability cannot be used if a Hero does not have enough Mana to cast it, or if it is on Cooldown. Mana will regenerate over time, and its rate of regeneration can be increased or restored by certain items. Cooldown prevents powerful Abilities from being used constantly. Cooldown will go away over time. For example, Huskar's Inner Vitality has a Cooldown of 25 seconds. That means that Huskar must wait 25 seconds after casting Inner Vitality before he can do so again, even if he has the Mana required. The Refresher Orb will reset all Cooldowns immediately when used, at a high Mana cost.

Attributes
In addition to unique abilities, every Hero has a different set of Attributes which control their initial statistics. These Attributes are Strength, Agility, and Intelligence. In addition to bonuses earned by each Attribute, Heroes also have a "main" Attribute. Every point in their main attribute adds 1 to their physical attack damage. Typically, this will also be the highest Attribute at first level, and the one that receives the greatest increase as a Hero levels up.

Every point in Strength will... Every point in Agility will... Every point in Intelligence will...
 * Increase the Hero's maximum Health by 19.
 * Increase the Health regeneration of the Hero by 0.03 Health per second.
 * Increase the damage of Strength based Heroes by 1.
 * Increase the Hero's Armor by 0.14 points.
 * Increase the Hero's Attack Speed by 1 point.
 * Increase the damage of Agility based Heroes by 1.
 * Increase the Hero's maximum Mana by 13.
 * Increase the Mana regeneration of the Hero by 0.04 Mana per second.
 * Increase the damage of Intelligence based Heroes by 1.

Heroes will earn additional attributes whenever they level up, but can also receive bonuses and penalties from items and some abilities.

Experience
In order to level up, Heroes must earn Experience. When a unit dies in Dota, it gives experience to all Heroes in a 1200 AoE based on its level. Experience is split among all Heroes in the AoE. If a Hero is killed more than 1200 units away from their killer, the killer still gains a share of Experience. Allied unit deaths do not grant Experience.

Denied units will grant a fixed amount of Experience, either 36 for Melee Heroes or 18 for Ranged Heroes. This Experience is still split among all Heroes in the area. Additionally, summoned units will only give half of their normal Experience when killed.

Armor
Armor is an attribute shared by all units. It reduces the amount of physical damage a unit takes, but can also increase the amount of damage a unit takes. The amount of damage a unit takes gets reduced if its armor value is positive, and increased if the armor value is negative. Armor is increased by Agility, certain spells and when you obtain items that increase armor

Magic Resistance
Magic Resistance (sometimes called Spell Resistance) is an attribute of heroes (and some other units) that reduces magical similar to Armor. All heroes possess 25% base Magic Resistance from their Armor type. This resistance is independent of the amount of armor they possess.

Last Hits and Denying
Last Hitting is the act of a player timing their attacks so that their Hero delivers the killing blow to a Creep, Hero, or Tower. Earning a Last Hit on a Creep will give the attacking Hero the Creep's bounty in Gold, while Last Hitting Heroes and Towers will earn large bonuses to the Gold earned. Denying involves killing friendly Creeps, Heroes, or Towers so that enemies do not earn bonus Gold. Denying will also reduce the Experience earned from a kill.

Buildings
Buildings are special units in the game. There are several types of buildings. They are immune to almost all spells, which makes them very strong earlier in the game.

Ancients
Ancients are powerful structures. The goal of each game is to destroy the enemy's Ancient. Ancients have 4250 Health and 15 Armor. They're guarded by 2 Towers that must be destroyed before they can be damaged.

Towers
Towers are defensive structures that guard the lanes and base of each faction. Towers will fire high damage projectiles at nearby enemies, but provide large amounts of Gold when destroyed. Either faction has 3 towers in each lane that become progressively stronger the closer they are to the main base. To attack Towers further in the lane, the outmost ones must be destroyed first. Additionally, each faction has 2 towers defending their Ancient. When any lane's towers are down, these become vulnerable. Both must be destroyed before damage can be done to the main structure.

Barracks
Barracks are structures inside each faction's base, near the ramps. When a Barracks is destroyed, the creeps of the opposite faction receive a health and damage boost, and provide less experience and gold when killed. This means that destroying a Barracks will ensure that your creeps will continue to push a lane without the intervention of Heroes.

There are two separate Barracks at each entrance, the Melee Creep Barracks, and the Ranged Creep Barracks. The Melee Creep Barracks will power up Melee Creeps, while the Ranged Barracks will improve Ranged and Siege Creeps. When all Barracks at each entrance are destroyed, the opposing team will receive Mega Creeps, which are far more powerful than their normal counterparts.

Fountains
The Fountains will regenerate Heroes back to their maximum Health and Mana over a very short period of time. Additionally, Fountains will attack enemy Heroes that attempt to enter their range, dealing 190-199 physical damage over 800 range and firing very rapidly. Fountains will fill Bottles back to full, if they are not already.

Cleave Damage
Cleave makes a melee unit's attacks deal a portion of their physical damage to the enemy units in an AOE. The damage dealt by Cleave is reduced by Armor type but not by armor value and is derived from the actual damage of the attacking unit as opposed to the damage that the primary target took from the attack. Also, cleave does not affect the primary target of the attack. Cleave damage does not increase based upon the effects of most unique attack modifiers you may have. If you have a Stygian Desolator and a source of Cleave and you attack a unit, only the main target of your attack will receive the Corruption buff from Stygian Desolator. The only buff placer that affects Cleave is Critical Strike. If you proc a Critical Strike when you cleave, the damage multiplier will affect all units hit by the Cleave. Multiple sources of Cleave work completely independently from each other. If you have a 500 AoE 50% Cleave, and a 250 AoE 35% Cleave, you will deal 50% of your damage in 500 AoE, and 35% of your damage in 250 AoE. Each Cleave source causes another instance of damage for the affected units. Cleave AoE is a circle with radius equal to the Cleave range, and its center at a distance equal to the Cleave away from the attacking unit, towards the primary target of the attack.

Unique Attack Modifier
Unique attack modifiers 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, unique attack modifiers, 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 unique attack modifiers. Not all attack modifiers are unique attack modifiers.

Damage Types
In Dota 2, there are several different types of damage that can be cause by abilities and spells. Each type varies in how it affects enemy units. These types are Magical, Physical, Mixed, Pure, Chaos, and direct HP Removal.