Raise your hand. I'll teach you this move today. Once the battle starts, use all your strength to swing it forward. Then, you pull it back. I calculated that you can swing it back and forth for at most 30 seconds.

In these 30 seconds, you're in your best condition. Gripping tightly and seizing the moment will give you great results. Please check this

What happens when a whole bunch come at once?

Why worry about so many at once, just care about hitting one at a time. Remember to take them out one by one.