|"You belong in a museum!"
|Utility Mastery Tree|
|Other Mastery Trees:|
|Offense · Defense|
Effect per rank
- Reduces the cooldown of Summoner Spells by 4 / 7 / 10%.
- Requires 4 points in Utility
- Mastermind stacks multiplicatively with and , and applies before flat cooldown reduction from effects such as Summoner's Insight.
- In Seasons One and Two, Mastermind was the final tier in the Utility tree and granted 15% cooldown reduction for Summoner Spells.