Below is a comparison of each healing classes 'big' relic heal, with mana cost, cast time, amount healed, and ratio of points healed per mana point:
Shaman with Woundbane, base:
-285 mana, 3.75 cast time, heals for 1650, 5.7
Cleric with Light of Eternity, base:
-395 mana, 3.50 cast time...