I'm very intrigued by the new keyword Fight, as used by Prey Upon. This deck's goal is to make it more than just removal.

It makes Sengir Vampire , Protean Hydra , and Lumberknot stronger while taking out blockers.

It turns Deathtouch creatures (Deadly Recluse, Vampire Nighthawk, and creatures affected by Onyx Mage ) into 1 mana sacrificial (potentially) removal.

Fume Spitter is a great card and I can burn my Protean Hydra with it.

Snake Umbra / Mask of Avacyn gives Protean Hydra almost immortality (buff to toughness prevents dying in combat and Totem Armor defends against Destroy cards), along with an ability to fix some of the card disadvantage I've accrued. Vines of Vastwood/ Giant Growth will protect it against everything else.

Same pretty much applies to Sengir Vampire (except the impervious to damage part). He's my evasion finisher.

Noxious Revival gives my deck a few more chances to use the limited Fight cards (or screw with my opponents drawing).

Questions:

Is the overall concept bad? Too many 2 for 1's?

Is Predatory Urge so bad I shouldn't bother? With a toughness boost on the Hydra I can make it target itself with the ability. Plus it just provides another instance of the theme. I'll take suggestions for replacing these with something else.

Should I replace the Doom Blades with 2 more Naturalize or something like it? Thinking about putting in Dismember if I can get my hands on it.

Is Onyx Mage necessary with the other deathtouch creatures I already have in there? I took out 2 in favor of more Vampire Nighthawk's, but also thinking of replacing the other 2 with Fauna Shaman (although it doesn't really add anything to the theme) or Oona's Prowler.

I would add a Vigor to this deck also if I could pay for it.