I'm not sure about building a strategy around goblins; they're too easily wiped out when they're not enraged. The enemy hero usually moves before them. After assessing the probabilities of various unfavorable outcomes, you can throw something powerful at the goblins or control them, and then use them to attack the cyclops (for example).
The "Protect Us All" skill in version 3.1 only allows for a maximum of 120 goblins, so that's nonsense.
I think that if you take "Empathy," you don't need to upgrade "Screams"; the hero will move frequently enough anyway.
Overall, it's an interesting and unexpected strategy for the opponent.