Arcane Will

Regenerate 5 Mana per second
30% increased maximum Mana
+10 to Intelligence [1]

Arcane Will is a notable passive skill that grants increased maximum mana, additional flat mana regeneration and additional intelligence.

Anointment

Blight anointment to unlock the passive:

Oil #1	Oil #2	Oil #3	Outcome
Amber Oil	Amber Oil	Silver Oil	Arcane Will	Regenerate 5 Mana per second 30% increased maximum Mana +10 to Intelligence

Version	Changes
3.16.0	[Undocumented This change was not documented by any official sources. It was discovered through player testing or datamining.] Now grants 30% increased maximum Mana (up from 20%) and Regenerate 5 Mana per second (up from 3). No longer grants 20% increased Mana Recovery from Flasks or Gain 3% of Maximum Mana as Extra Maximum Energy Shield. Instead, it now grants +10 to Intelligence.
3.11.0	Now grants Regenerate 3 Mana per second (up from 2) and Gain 3% of Maximum Mana as Extra Maximum Energy Shield (down from 4%). [Undocumented This change was not documented by any official sources. It was discovered through player testing or datamining.]
3.4.0	Introduced to the game.