I just beat Namtar's Lair with the new vicious token and didn't get the badge, or any recognition for it. The new badge is still darkened on the kingdom screen. I did restart a few times before the winning run, but I'm certain the token was active - Namtar wasn't a pushover like he usually is.
EDIT: I'm pretty sure now that I forgot the Vicious Token on this run. At least, I haven't been able to replicate the "bug" (i.e., beat Namtar