Rule 391

Delayed Abilities will resolve or be active just like the ability they augment, but only during the specified time in the effect that created the Delayed Ability. Example: Ravenborn Tome reads “The next spell you play this turn deals 1 Bonus Damage.” This is a Delayed Passive Ability that passively adds 1 Bonus Damage to just the next spell played. The next spell is a specific time, and the 1 Bonus Damage is a passive ability. Example: Noxian Guillotine reads “Choose a unit. Kill it the next time it takes damage this turn.” When the chosen unit takes damage is the specified time, and killing it is the condition for a Delayed Triggered Ability.