I think Holy light just doesn't have the chance to be good. Compared to Luciferin, in the most cases, Luciferin do the same as Holy light, Luciferin works well with Hope or with unupped monolight rush (light dragons and Photons doesn't have ability). Holy light can heal creatures, but if a creature survived 10 dmg (which is not a common case), it's given so much quanta and card effort. And this only can used, IF the creature is still alive and the creature worths healing. It has a special CC ability, but Darkness creatures can die very easily, Death either by low life points. And it's not targets Entropy.
I rather want to see the Luciferin with creature healing too and take this card out of the game. I like this card, because the upped is for free, but I won't see if that card could be used in the near (or far) future without drastic changings.