Hi there!
The first thing I noticed was that both
Foreboding Ruins and
Smoldering Marsh will come in tapped without using basic lands, which you don't have any of. Then all your other land except for
Aether Hub enters tapped as well. This is going to slow your deck down, and having most of your creatures costing you six mana that isn't a good thing.
I think you need to focus on how you want this deck to work. Right now it doesn't seem like the cards interact with each other. It looks like your relying on
Murder and
Nahiri's Wrath to accomplish things earlier in the game, then getting a little graveyard retrieval for those discarded cards.