I agree,
fantastic art. Loving the way the blue light is cast on the lion's nose.
This is a very interesting card concept, with some really cool strategic implications I think people are forgetting about. One major strategic possibility is using this on your own creatures in order to prevent the negative effect of a shield - I have actually used Sundials for that very reason in the past! Like say I don't have my Pulverizer yet and I'm fighting Neptune and my Otyugh is already down. If I chain a couple Sundials, I can grow him past 2 attack without danger of freezing. This tactic doesn't seem too useful to Light mono, though - I'd use it more in duo/trio decks.
Since this is a temporary effect and only cripples attack, I really want to see this target immortals. Quintessence is usually used to protect creatures with important abilities, like Otyughs and Druids and Firefly Queens, so their abilities still wouldn't be harmed. It would open up the possibility of stalling a quinted Growth/Ablaze creature, a Phase Dragon, etc., without breaking your opponent. But I doubt Zanz is going to consider making an exception to quint's targeting ban anytime soon...
Of course any kind of coding is possible, but I wonder how exactly coding this would work? There are a couple ways to go here. The attack could be stored and the creature's current attack set to zero, then the old attack read after a few turns and re-applied. Or make a new kind of status (รก la momentum, adrenaline) that simply stops the creature from attacking until the counter expires. These two also have different implications when the creature in question is able to use Growth or Ablaze... should it be able to grow to 2, 4, 6 while it's gentled? Or will growing do nothing? Or would the cumulative stacking be applied to the attack after the gentling has expired?