I don't think this card would be very good. It's basically a Cone of Cold except that it doesn't do any damage and you can't actually position it yourself to make it most optimum.
If it did 1 damage to those minions then it might be more competitive.
Goodness gracious. For 2 mana it shouldn't be doing that much.
Cone of Cold is 4 mana, 3 freeze, each get dealt 1 damage.
Half the mana, half the effect. It being a secret is a plus, since it can be pulled for free from Mad Scientist.
It's just meant to be a stall tactic. Frost Nova, for instance is 3 mana to freeze minions without dealing damage. Arcane Blast, which is 2 mana, deals 1 damage.
Just to put it into perspective.
Hunters are about putting on the hurt. Freezing the opponent's board for a turn would be fantastic for Hunters. Especially if it was for free from le scientist.