At first, it was a light shower of rain. Ten minutes later, however, it had become a massive rainstorm. This was weather that both sides preferred not to see, but the undead held more of an advantage in such weather.
Perhaps it would cause the undead's reinforcements to arrive slightly later, and the undead would be slightly affected by the torrential downpour, but it could not significantly influence their situation.
However, this was doubtlessly unpleasant weather to be fighting in for the defending adventurers. With such a mega rainstorm, ordinary humans on the attacking side would most likely choose to rest in this weather as well. After all, the current temperature was still rather cold, and even the average strong human wouldn't be able to handle vigorous exercise and sweating in the rain, which would easily lead to them catching a cold. It was quite common for even powerful individuals to fall ill if they fought in such weather.