Invisibility

When a hero is invisible (sometimes shortened to 'invis'), it does not appear on the opponent's screen or minimap. Heroes can become invisible by using skills, the items Shadow Blade and Smoke of Deceit, or by acquiring the Rune of Invisibility.

A unit will stay invisible until its invisibility timer runs out, it attacks an enemy, it casts a spell, or uses an item. This is the basic rule and there are some skills that deviate from it.

Disjointing
All ranged attacks and most spell projectiles can be disjointed (it will no longer damage or affect you) by going invisible before it hits you. Note that it will not work if the enemy has sight over your hero.

Revealing
There are several ways to reveal an invisible unit:
 * True Sight: The most common way of revealing enemy units. This is usually done by Gem of True Sight, Dust of Appearance or Sentry Wards.
 * Units that are entangled or ensnared will not go invisible until the effect wears off.
 * Hero Abilities: Some heroes (like Bloodseeker) have an ability that allows them to track invisible units. These abilities can either reveal the invisible unit, or merely show its location on the minimap. If it only shows the location, the unit can still be attacked by auto-attacking it.

Area of Effect Spells
Some area of effect spells affect invisible units (Pudge's Rot) while others don't (Earthshaker's Echo Slam).