Usage of Soothing Sunlight requires that the caster belong to the Princess's Guard covenant. It restores a high amount of HP for the user and also any friendly phantoms around them, including NPC summons and enemies affected by Undead Rapport.
Soothing Sunlight benefits from miracle synergy.
Health restored ≈ (6 * mag adj) + (4.2 * synergy (0, 1 or 2))%
Tested in-game examples:
- 165 mag adj = 989 with 0 synergy, 1,031 with 1 and 1,072 with 2.
- 219 mag adj = 1,314 / 1,368 / 1,423.
Given the fact that it requires membership of the unpopular Princess's Guard covenant and also the exorbitant faith requirement, Soothing Sunlight is a rare sight indeed. Also, it takes coordination for allies to get close to someone who is about to cast this miracle, and communications in Dark Souls is both time-consuming and limited. Ultimately, this limits Soothing Sunlight's practicality as a healing miracle.