[rdonj]

As an alternative to a bio-shield, you could couple high prot with a decent amount of health and fast regeneration or luck. But cause them to gain fatigue as the fight goes on. It would be like when they're in the cocoon form they massively speed up their metabolism to keep the cocoon intact while people are trying to destroy it. But eventually they start running out of energy and it becomes easier to destroy them (by scoring critical hits and getting throught their protection faster).