William also noticed their ability to heal from wounds, even high-grade ones could regenerate any severed limbs in mere minutes.
But that didn't mean they were indestructible! Using brute force was enough to kill them. As for the weaker masters, they could collaborate together, and work in teams, to take down these monsters.
William kept fighting for half an hour, while the formidable masters decided to throw themselves in the middle of the incoming monster tide and see things through by force. As they started to fight, they noticed what William noted before, and they knew these monsters weren't that scary after all.
"Advance! Work in teams to take these down! Don't fight them solo, they got strong shields to protect them from most damage," the moment the leaders and top masters realised the ins and outs of these monsters, they instantly relayed the news back to the army waiting behind.