Any magic type monster was weak and could be easily defeated as compared to a physical attack type monster, but when fighting with multitude of them, it did not matter how strong you were, the blast from the arcane magic was enough to send you to the grave!
The party did not dare to pull too many monsters in at one go and only took two or three at a time. Even though the killing speed was faster than killing one at a time, the efficiency was much lower than killing a large bunch like in the first floor. Thus, the progress was obviously slower, and the accumulation of experience points was slow as well. Still, this was just between the first and second floor, and the progress was better than grinding alone.