I'll just say it flat out: This vicious reward is subpar. The concept is interesting, but resists are suited to a brawler while damage on kills is much more of a striker ability. To show you this isn't baseless, let's compare it to the other rewards:
Namtar's Ward: I love it. This prep is great for all classes, but especially rogues and berserkers. I prep it for most of my normal and hard runs.
Dragon Shield: Great. Probably the best prep in the game tied with the Tri-Sword. It depends on the class build.
Naga City: It's undecided. I won't compare.
I think the item needs to be much more focused in. It is mediocre for two types to builds, but good (in comparison to other preps) for none. I literally have never had a reason to prep it. Not to mention it's tied for most expensive locker item. Right what the vicious items cover are brawler (Dragon Shield), spellcaster (one of the two Naga City items), and general (Namtar's Ward, although it leans striker). We should focus the symbol on its striker side. I think just replacing the resists with +6 or so base damage. Then I'd definitely prep it.
What does everyone think?