When a Mystic heals using their Vitality Network, is the Harmony effect from their connection mandatory? or optional? It sounds mandatory from the wording, but some Harmony effects are significantly less useful than others, and in fact some can actually hinder the target of the healing.
Healing Harmony is excellent, but in contrast, Shadow and Elemental seem to have the potential to be detrimental effects.
Shadow Harmony is detrimental when used on an ally that doesn't have low light vision, or requires targeting by an ally that can't see them well in dim light.
Elemental Harmony forces the healed target to do a specific type of damage if the Mystic's epiphany is active, which can penalize their damage against resistant enemies or even useless against immune enemies.
I will probably make the harmony effects optional in my games.