Board Thread:Questions and Answers/@comment-88.199.132.125-20151017193250/@comment-26569935-20151018005145

I would say heavy is when 30% to 50% of an army is wiped out, while massive is when you lose more than half. Like Stannis started with 25,000 men before the Blackwater and ended up with less than 5,000. That's 80% of his army gone.

So I agree with TDD.