GY sac, gnaticide, heals

Healing cards: Hold the line!, Gaea's grace, Storyteller, Radiance.
Gaea's grace can easily be replaced by soul drain.
Storyteller provides a card draw, which is very useful for this low-faeria cost deck.
Hold the line! is very strong with this deck: 2 minions with taunt and heal
Radiance is a bit tricky, because the deck has many heals, but with around 10 cost it can be efficient card.

Sacrifice cards: Demon wrangler, shaytan assassin, lord of wastes, death walker
These cards have obvious uses. Oath to oblivion and Doomgate can be considered, but they are too dependent on gnat so I didn't find them efficient.

Self damage cards: Soul pact and Gnat. Once you draw Gnat this deck really starts rolling. But you only need one. If you draw 2 the second is wasted. I seriously consider leaving only 1 gnat and squeezing 2 iona's smiles in the deck. You don't really need more self damage. 2-3 times is enough to make wild avenger efficient. Altar of souls is also a very good choice but it's a bit slow because of the 3 land requirements. It still might be worth it though.

Objective: Obviously, the objective of the deck is to buff soul eater and wild avenger, the core cards of the deck.

Supplementary cards: Earthcraft, spirit of rebirth. Earthcraft could be replaced with wood elemental, depending on preferences. Spirit of rebirth isn't essential, but provides a strong and efficient bonus.