Ice Nova is one of many spells. It requires level 10 to unlock, and costs 15 mana to cast. At higher levels, it increases damage, size, and slow amount. It looks like a ring of frost expanding from the character.
At level 6, Ice Nova's base damage is 200. For every point of intellect, it deals 4 more damage.
Each upgrade level costs 2500g, the same as the base. Level 6 costs 25,000g or double the cost of the previous level.
It's cooldown, at every level, is 15 seconds.
Despite stating that the size will increase, it always has a burst of the same size, approximately a ring between the first and second item slots for distance.