Co-op vs. AI

Co-op vs. AI is a game mode in League of Legends where a team of players are matched against a team of computer-controlled champions commonly known as bots. The team sizes are the same as in normal player versus player matches, but the variety of game modes has been reduced.
 * Co-op vs. Ai.png on the Co-op vs. AI banner.]]

Description
Co-op is available on The Crystal Scar (Dominion mode), Twisted Treeline, or Summoner's Rift (classic mode). There are two difficulties to pick from, Beginner and Intermediate. A player can either play alone or invite their friends to join them. If the composed team has less than 5 players, the matchmaker searches for other players wanting to play at the selected difficulty. The co-op matchmaker works similar to normal games, but considers the players level instead of their Elo Rating. First Win of the Day IP bonus is available and Elo Ratings are not affected.

Co-op vs. AI rewards are slightly higher than custom games but lower than normal games or ranked games. Here are the current rules for Co-op vs AI rewards:
 * All summoners can earn unlimited rewards per day in Co-op vs. AI. However, level 15+ summoners can only earn 75% of the normal Co-op vs AI rewards after 180 minutes.
 * The following modifiers are applied based on summoner level and bot difficulty setting. These percentages represent how much of the standard reward is received:

There is a pool of 56 champions that the bots can be picked from. They are as follows, listed within categories according to five major roles :

Bot behavior
Bots have different behavior and advantages depending on the difficulty selected. Some behavior is standard, regardless of difficulty selected. Most notably the bots will not jungle or pursue creep buffs, though the bots on the Crystal Scar and Twisted Treeline maps will actively acquire altar and pad buffs located around the maps. The other universal behavior is a faster revive time if killed. Bots will occasionally chat at the beginning and end of games.

Beginner

 * The bot pool has less variation, as the game draws upon a smaller selection of champions.
 * The bots use less advanced tactics and do not gank as effectively.
 * Bots do not receive any rune or mastery bonuses, or some type of equivalent.
 * Bots do not use any summoner spells, despite equipping themselves with 2.

Intermediate

 * Bots do not need line of sight to target their abilities. For instance, if a bot or nearby enemy minion sees you enter the bushes then the enemy bots are able to directly target you in that bush for several seconds (as if it was warded). This differs from human opponents who would need to face check the bush (if not warded) to use direct target abilities.
 * The bots will use more advanced tactics. This includes switching champions around in lanes, trying to gank often, or more rarely trying to push a lane with three champions within the first ten minutes.
 * The bots will still gain items even if they were gold starved in a lane. This suggests that they gain items based on level or have increased gold over time.
 * Bots don't have runes or masteries.
 * Bots will use alternate champion skins, which may cause confusion.
 * Bots will actively use summoner spells.

History
Co-op vs. AI was first announced on LeagueofLegends.com on January 20th, 2011, as a new game mode intended to prove a harder challenge and training method for players rather than just the bots available through the custom game option.

A match showing a fight between some of the new bots versus mid-level Riot Employees was announced on February 4th to take place on February 9th. This battle was streamed through Own3d, and resulted on a close (and sketchy) victory for the Bots.

It was intended to be released on the week following the V1.0.0.111 Patch, but it was delayed because the European servers were not ready to take on the increased stress that would be caused by the game mode.

It was finally released on a Thursday, on March 10. It supported two difficulty settings, Beginner and Intermediate, and a pool of 12 bots available only on Summoner's Rift.

Rise of the Bots Update
On January 24, 2012, Riot released a news post announcing an update to the Co-op vs. AI game mode. This update was put in place on February 1, 2012, with the V1.0.0.133 patch. The new features and upgrades included the following:
 * Bots made available in the Dominion game mode, which its co-op option was unavailable at the initial launch until this patch.
 * More intelligent bots with increased map awareness, capability to use skillshots as well as more summoner spells and active items.
 * The flat IP penalty for Co-op versus AI games was removed. The rewards were also changed to make the mode more attractive.
 * Increased the roster of bots from 12 to 40. Also, more champions are being added in the subsequent patches regularly.

Bots AI Updates
This update was put in place on April 16, 2014, within the V4.5 patch. The new features and upgrades included the following: Additionally, the devs made a blog post to explain the reasoning behind the changes.
 * Improved evaluation of enemy and friendly strength.
 * Improved understanding of tower mechanics and power.
 * Improved behaviors while under high threat.
 * Improved lane rotation decision making.
 * Improved last hitting with auto-attacks both when farming normally and when pushing.
 * Lane behaviors (harassing vs. farming, etc) are now more in line with human behaviors.
 * Bots now attempt to dodge some skill shots.
 * Beginner bots now build recommended items, while Intermediate bots now make more advanced item choices.
 * Bots now scan their surroundings at variable rates depending on difficulty setting and in-game threat level.
 * Beginner bots now scan at roughly one third the frequency they used to, while Intermediate bots scan anywhere from 50% to 100% as often depending on how threatened they are.