The Mana Reservation Efficiency mastery has been replaced as there is now a much larger amount of Mana Reservation Efficiency for Curse Auras on the passive tree." (The mastery was 30%) :
Petition for Enlighten gems to also use Reservation Efficiency for supported gems instead of a mana multiplier : r/pathofexile
POE 3.19] How to Fit More Auras and Fix Your Mana Cost! Mana Reservation & Cost Guide - YouTube
Just a heads up if you're reserving your life with the new "Blood Magic" : r/pathofexile
Reservation - Path of Exile Wiki
Enhance Support PoE Leveling Fast, Drop, Farming, Increased Experience Gain 3.22
1 to ALL Intelligence Skill Gems & Zealotry 25% REDUCED Mana - 193 - YouTube
Gameplay Help and Discussion - Mana Reservation Rounding Question [pics] - Forum - Path of Exile
Reservation - Path of Exile Wiki
Gameplay Help and Discussion - Impresence Flammability 100% Reduced Mana Reservation is BUGGED. - Forum - Path of Exile
TIL there is a cap on gem level : r/pathofexile
Path of Exile Skill Gem Reduced Mana - YouTube
Aura | PoE Wiki
Getting Stronger Guide - Path of Exile - Maxroll.gg
Development Manifesto - Aura Reservation and Reduced Mana Support Gem Change - Forum - Path of Exile
Bug Reports - Corrupted jewel mana reservation does nothing - Forum - Path of Exile
Reservation - Path of Exile Wiki
Awesome I got mana reservation...Oh : r/pathofexile