Seems like a burst damage like spark, but not a particularly effective one, with only 4 attack. It is cheap, which is good and helps balance it. The wording leaves it a bit ambiguous as to what exactly happens when frozen. Does it freeze and gain +1/+1, or does it not freeze at all but get the boost?
Overall, it seems underpowered. I suggest +1/+2 when frozen, so that it works similarly to growth. Instead of just keeping the snowman from melting and very slowly gaining attack, and being very vulnerable to CC, it should at least show a positive stat gain. In addition, as with some other water cards, flooding should affect this somewhat, seeing as snowmen are made of water. Maybe double the stat boost if in a flooded area, or just make the melting not apply anymore? Also, the unupped version seems even less useful. It simply dies to quickly to be of use. For both versions, the attack efficiency is the same as Minor Phoenix, 2 quanta for 4 attack, but this dies in 3/5 turns, whereas phoenix can last virtually indefinitely.
