It was impossible to come out completely unscathed. With so many opponents, the only thing Zheng Yichen could do was to minimize the chances of injury from all aspects. The unavoidable part of it—well, he would just not avoid it. If he was seriously injured, he would abandon the subsequent action and very decisively run out of the Alien Phenomenon. Once he recovered in a normal environment, he'd take action again.
The number of Boundary Breakers was substantial. Every time a few died, they shouldn't expect to have it easy. But if he really made it out, he would definitely first raid the military camps he'd encountered before, equipping himself thoroughly before returning.