I believe there is a Berserk out of TC, but i don't believe you can actually get it in the deck. My friend has the Berserk card from one of his amulets i believe. One card from an amulet might not seem so much, but it saves a lot of gold over time.
You can only get it as a regular spell if you are a Death wizard. If you train Death as a secondary school, it's not one of the spells you can train for. So, TC is the way to go for all schools, except for Death.
EDIT: Oops, I totally forgot it was a Sun school trainable spell, so please accept my apologies for the error.
You can train it but if you do use it, you will only use it until AZ and you unlock the higher level spell that gives multiple boosts. I trained it because I had so many training points. I experimented and could never find a way to properly use it effectively, so it never made it into my deck. Later on in the game you will not use it. Virulence (death bubble) gives like 25% damage boost, pip boost, and only a 10% incoming damage to 1 school. Berserk might be useful if the damages were swapped, like 40% boost and 30% incoming. As it stands now it is not a worthy trade off.