There was a nice trick that Karoline accidentally discovered, which was by kicking the enemies off the hills when she got surrounded by three of them.
Sara handled one, Berry stopped the second, while the third got no one to stop him. But unlike what anyone expected, Karoline jumped in the air all of sudden, kicked him in the chest, and sent him flying backward.
She wasn't strong enough to harm this master, but her kick sent the man flying, crossing the edge of the hill they were standing upon, before free-falling to his doom, down to the ground.
"Let's do this!" as everyone saw this, they realised they could use this method to solve many problems here. And once they started doing this, they picked up pace again, gained momentum, and started pushing through lots of dark masters.
Yet they weren't able to cover up the entire place in the short time they had. William was already standing at the tower base when he got attacked with many arrows coming from different directions.