3 or 4 more HP for Light mark looks very weak. SoS really prefer Death element, SoR the same with Time. Here I didn't see it.
Maybe adding HP from SoD should depends on HP Light creatures on the field (max 30-40HP), or from Light quantum? Or maybe this Shard should also heal Light creatures?
Heal cost 2 and gives 20 HP (and possibility for EM).
SoD cost 3 and gives 22HP (less chance for EM, You must use other card)
I absolutely agree with that.
SoD is rare card, isn't it? But in my eyes, it is look like normal card marks as other. Then, when it is compared to Heal, SoD has weaknesses.
In summary, SoD needs more buff and more "game breaking" feature like other shards. SoD also needs something that give more advatages to light..
I suggest: SoD give (22 + 3 * light emmiting creatures in the field) to max hp.
I means that more benefit to deck that use creatures of light. Also means luciferine is have more benefit here. So, it is better.
It is also motivate to creative and unpredictable game. More light emmitting creatures means more max hp will be added. It has more chances to game breaking. (but, setting up light mass emmitting creatures is also so difficult..)