I do have a recommendation or two for this deck:
1. if you are going to add red creatures to this deck then you may want to consider adding some mountains to this deck. Reason being is that
painted bluffs is the only red mana producer that I see in this deck. You want to have at least 3 or 4 mountains in this deck so that you don't get stuck with a
dead hand
2.
Soulstinger +
consuming fervor will give you a lot of -1/-1 counters and will be a good beater to have on the field. It's strong and it'll combo well with your
nest of scarabs when it dies.
3. You may want to remove the
grasping dunes in exchange for
splendid agony. This way you have an instant that places more than one -1/-1 counter on creature(s) and it's an instant so it can be used as a kill spell.
4. If you focus less on the discard outlets of this deck and more on the -1/-1 counter production of this deck it'll run faster and smoother for you.
These are just some points that I thought I'd bring up for you. What do you think?