The Eye of the Herald is a neutral buff that is gained upon securing the eye that spawns after slaying Rift Herald. It is available only on Summoner's Rift.
The eye can be picked up by moving near it, and will otherwise disappear after 20 seconds. Only members of the team that killed the Rift Herald can pick up the eye.
The Eye of the Herald also replaces the trinket item in the trinket slot, which prevents purchasing trinket items until it has been consumed. Consume the trinket to summon an allied Rift Herald that aids your team.
All players are alerted by a cry as an audio cue for when the Rift Herald is summoned.
While there are no allies nearby, you take 5% damage reduction from enemy champions and generate X / Y (based on level) Corruption stacks per second. At 100 stacks, your next basic attack consumes all stacks to deal 15 / 270 (based on level) bonus magic damage. Works versus structures, damage halved for ranged champions.
Lasts for 20 minutes and is retained even if slain.