Actually all 3 healers have exactly two ways of Mana regen.

  • WHM: Assize and Shroud of Saints
  • AST: Ewer and Lumineforus Aether
  • SCH: Aetherflow and Energy Drain
This extends to the rest of the Disciplines of Magic as well
  • SMN: Same as SCH
  • BLM: Convert and the Blizzard spells
Of the 3 healers, WHM is simply the most dependable since both Shroud and Assise can eb woven in and have no RNG elements like Ewer or opportunity cost like Energy Drain. But they all have 2 ways of getting mana