I'd be happy with a 25% nerf to Frostbomb damage and a 50% buff to Frost Bolt damage, honestly. The Mage I play with said he never even bothers to cast Frost Bolt anymore because he'll only ever get kills during Frost Bomb, so he just spellsteals / gets in the right position / icelances until then.
Our Win/Loss in 2s is 50-6 or something. You don't want to know the amount of games we've won in the first Frost bomb.