There are many "evil" things within the forest, unfortunately. 9S and Elsword dealt with one of them some time ago... though I wouldn't call Moder "evil" per se.

[It's a subjective term. The Trader continues:]

Anyone who has to field as much corruption as that old gargoyle does is likely going to weaken after some time. If he's calling to you at all, he might be in danger.

[Which, you know, bodes well for us all, surely.]