I’m not a huge fan of your creature selection. You don’t get down any meaningful pressure until turn three and that’s just not it. You’re never going to get under the decks that can go over you like that. I know Scarab God is a heck of an endgame, but there will be times you just need to end a game quickly, or throw out meaningful blockers early. Tenacious Underdog is an all star. I had two in my Orzhov midrange deck last time I took it to FNM. It single handedly drew me five cards late on when both me and my Golgari opponent were hellbent and with vast tracts of lands in front of us. He won me the game. I now have the full set. He’s really good. Also worth considering Malevolent Hermit depending on what your local meta game is like. You also need blockers early against the aggressive decks. A set of fatal push and Aetherborn isn’t going to stop mono red or heroic. Underdog is a relevant body, albeit one that dies to stomp. It’s a bit out there, but I’m planning on testing Concealing Curtains next Friday. Blocks for days against aggro, maindeckable hand disruption that’s attached to a relevant clock against control and combo. It’s also hand disruption you don’t feel bad about keeping in in midrange mirrors where traditionally Thoughtseizes are the first thing that get cut. Not saying the curtains are good enough, I don’t know yet, but I feel like they could be. They’re Thought-Knot Seer at home and I loved that card when it was in standard.

So yeah. More cheap threats.

I also, personally, wouldn’t want to rock a deck that wants to go for the long game without any removal that can tag big threats and/or planeswalkers. A couple of Bloodchief’s Thirst or Heartless Act worth considering maybe? Again, it depends on your local meta game.

Feel free to dismiss all of that. It’s all my own personal biases and I’ve never played Scarb God, I don’t really know how to build a deck around it. It’s just my thoughts.