Vision

Vision (or Sight) is an attribute of units and structures that allows players on the same team to see enemy units or structures, or to see things through the Fog of War. The Fog of War is the game mechanic in which a player's access to information is limited to the region of map which is currently revealed by his units, buildings, and abilities. It is represented by dark and light regions on both the minimap and the main screen. As a teams units move about the map they grant full vision to the team within the vision range of that unit. This is shown on the minimap as a fully lit region. When a team loses sight of an area, either by a unit moving away or dying, the map area reverts to a darker shade and any information about units is removed from the main screen and the minimap.

Gameplay

 * Every unit (Hero, minion, summons allied monsters and mercenaries) or structure provides vision of a certain distance, and this vision continues to be provided for a brief time after the unit or structure is destroyed.
 * Unless otherwise noted, heroes have a sight range of 12.
 * Most structures do not block vision. A units vision is not reduced by being on the other side of a Fort, Keep, Tower or Core. Gates and Walls however, do block vision.
 * Captering a watchtower provides vision in an area around it.
 * Most Terrain like rocks and trees block your sight.
 * Bushes, however, do block your sight, but can be seen through from the inside.
 * Units which are provided sight are able to attack units that they could not see on their own.
 * There are a number of abilities that reveals a Hero over terrain.
 * All projectile and AoE Abilites provide momentary sight in their path. Using a low cooldown ability before entering a bush is always a smart move.
 * Likewise, a Hero using an Auto Attack or an Ability from outside the enemies vision, does give away his position.