In Dark Souls, Great Heal is the miracle that restores a large amount of HP.
Great Heal is a stronger version of the basic Heal miracle. It restores a substantial portion of the caster’s health, making it valuable for Faith-focused characters and for long journeys where Estus supplies are limited. Like other miracles, it requires attunement slots and a suitable level of Faith.
The miracle can be obtained from Rhea of Thorolund after her storyline advances. Rhea is associated with the Way of White and can eventually appear in the Undead Parish after events in the Catacombs. Her inventory reflects the game’s distinction between ordinary healing and more powerful divine miracles.
Great Heal is not the same as Soothing Sunlight. Soothing Sunlight is a much rarer and more powerful healing miracle associated with Princess Dusk and the Sunlight Princess, while Replenishment restores health gradually over time.