Gameplay

DotA pits two teams of players against each other: the Sentinel and the Scourge. Players on the Sentinel team are based at the southwest corner of the map, and those on the Scourge team are based at the northeast corner. Each base is defended by towers and waves of units which guard the main paths leading to their base. In the center of each base is the "Ancient", a building that must be destroyed to win the game.
Each human player controls one hero, a powerful unit with unique abilities. In DotA, players on each side choose one of 108 heroes, each with different abilities and tactical advantages over other heroes. The scenario is highly team-oriented; it is difficult for one player to carry the team to victory alone. Defense of the Ancients allows up to ten players in a five-versus-five format and an additional two slots for referees or observers, often with an equal number of players on each side.
Because the gameplay revolves around strengthening individual heroes, it does not require one to focus on resource management and base-building, unlike most traditional real-time strategy games. Killing computer-controlled or neutral units earns the player experience points; when enough experience is accumulated, the player gains a level. Leveling up improves the hero's toughness and the damage they can inflict, and allows players to upgrade their spells or skills. In addition to accumulating experience, players also manage a single resource: gold. The typical resource-gathering of Warcraft III is replaced by a combat-oriented money system; in addition to a small periodic income, heroes earn gold by killing hostile units, base structures, and enemy heroes. This has caused emphasis on a technique called "last-hitting," which is when the player attacks a hostile unit when "its hit points are low enough to kill it with one blow". Using gold, players buy items to strengthen their hero and gain abilities; certain items can be combined with recipes to create more powerful items. Buying items that suit one's hero is an important tactical element of the mod. Item choice also affects play style, as any given item may increase one statistic while leaving another unchanged.
DotA offers a variety of game modes, selected by the game host at the beginning of the match. The game modes dictate the difficulty of the scenario, as well as whether people can choose their hero or are assigned one randomly. Many game modes can be combined, allowing more flexible options.