A few things:
1) The text needs to be much clearer. I presume this is appropriate to your intentions (it would apply to the upgraded card):
Shield: Reduce damage by 1. Reduce damage dealt by attacking Fire creatures by an additional 2. Reduce damage dealt by Fire spells by 3. If targeted with Deflagration / Explosion, deals 20 damage to opponent. Generates Congeal every 3 turns.
2) The cost of this shield needs to be higher. I suggest increasing casting costs to 6 / 8 Water Quanta and having the generation of Freeze / Congeal cost an additional 1 Water Quantum.
3) The name "Iceberg" is not very good at all. There is no conceivable reason it should be a shield, let alone a generator of Freezes. I would recommend a name that evokes an item name and an "icy generator" of sorts. (Just this once) you can steal a name of one of the spells from my card game: Ice Cradle. I think that works better. Or just Icy Generator for that matter.
4) This card is clearly anti-Fire and should be balanced by giving Fire an anti-Water card of equal power. The way to do that would be creating an offensive spell that is destructive (Fire's tendency). Maybe something like "Volcano" which destroys 3 Water Pillars / Pendulums AND deals 2 damage to all enemy creatures. Casting cost of 8 / 6 Fire Quanta.
