As the title says, I noticed that the build I used in normal runs of prophecy was working well against the minors and majors, but when it came to the boss it was significantly harder to achieve the one phase than it was on normal runs of prophecy. Not only that, the boss is more aggressive and tries to push you off the map more frequently, as well as moving around more during damage phases. I am not sure what caused this, but I believe the boss is coded to be at least Eternity level in Explorer mode.