Death

Death occurs when a champion takes sufficient enough damage to be reduced to zero health. Upon death, the summoner's screen is shaded gray, a death recap and death timer are displayed, gold is rewarded to champions who earned a kill or an assist, and other champion or situation-specific events may occur, as detailed below. The death of all five members of a team simultaneously is referred to as an ace; it is possible for both teams to be aced at the same time, and no champions to be present on the Field of Justice.

Death Timer
When the death timer reaches zero, the dead champion is revived on the summoner platform in direct proximity to the Nexus Obelisk and Item Shop. The exact formula used to determine the death timer's duration is unknown, but what is known is that the time spent dead increases accordingly with experience and match time. While the death timer is counting down, the dead champion is still able to shop for items, look around the map, and chat with other teammates. Ways to reduce the length of the death timer include the following:
 * mastery
 * spell
 * reduces death timers by 7 seconds, during which time he is able to cast abilities.

Removal of Stacks/Buffs/Effects
Upon death, if the champion killed possessed a buff or had built up stacks on one of a handful of items, those effects are either lost or transferred to the killer. If the champion killed possessed an innate ability, the bonus will be lost for the duration of that champion's death.
 * Effects/Buffs that are Lost
 * Buffs that are Transferred to the Killer
 * Persistent Effects lost during Death
 * Stacks lost upon Death
 * Buffs that are Transferred to the Killer
 * Persistent Effects lost during Death
 * Stacks lost upon Death
 * Persistent Effects lost during Death
 * Stacks lost upon Death
 * Persistent Effects lost during Death
 * Stacks lost upon Death
 * Persistent Effects lost during Death
 * Stacks lost upon Death
 * Stacks lost upon Death
 * Stacks lost upon Death
 * Stacks lost upon Death

Ways to Prevent Death when Reaching Zero Health
Effects that prevent you from dying always occur in a set order. From top to bottom, first is:

After-Death Events
Some champions have abilities that trigger after their death or the death of another targeted champion, allowing for limited control by one of the involved parties. These will only occur after the previously mentioned sequence.