Imposa apparently knew that the level of those monsters was too high. If they had gone on a rampage, they would have soon faced repercussions from Myers Mainland.
However, that silver fish was of a very high level—and it was highly intelligent to boot. Even if the berserk potion actually worked, it probably wouldn't have been punished by the rules right away, which meant that anyone who got in the way of its lethal attack would have been out of luck.
By charging at Saleen's face, Imposa was definitely up to no good.
The grand duke was livid about this! That was no way to treat an ally. Imposa was working for the grand duke, and his nefarious actions could have put him at odds with Saleen.
