Looks good to me!
Immurement is worth keeping. It's a tactic and it's your only support card control. Other than the Sewer Rats, you have limited direct removal for troublesome characters (such as Carl Stanford, Gustaf or Ravager from the Deep if your opponent is mostly playing Cthulhu) so it can potentially save you the game.
I find Immurement can be useful as a first-turn hit (before resourcing, so you only have to drain a 1-resource domain) to remove an initial character, and then play a character with investigation to go in unopposed.
My suggestion is to play this deck several times before making any tweaks (between 3-5 games). During play you'll start to learn which cards work for your playing style and which don't, what you want to see in your opening hand, if there are any interesting card synergies you missed on first glance but reveal themselves in play, and if there are any holes your opponent is constantly exploiting. Then come back here and share with us how it went.