Necrotic Sliver is great with an effect like Reya Dawnbringer or Sheoldred, Whispering One. Vindicate on a stick every turn.

I like Fleshbag Marauder better than the Reassembling Skeleton due to its interaction with Sun Titan.

Rule of Law, Lightmine Field, and Crawlspace are also good for when your win condition isn't combat.

Kismet works well with your Sphere of Safety. There's also Starfield of Nyx.

Updates:

• Expedition Map --> Authority of the Consuls: I don't need the 'big mana' lands that often and this is card is just too good to pass up.
• Archangel of Tithes --> Kambal, Consul of Allocation: I think Kambal will be a better fit (and maybe even an alternate commander)
• Painful Quandary --> Flickering Ward: Flavor for more efficient protection.
• Falkenrath Noble --> Soul's Attendant: less offensive, but more lifegain

@KaraZorEl

Thank you for the suggestions. I think the first two have way too high CMC for this deck. Fleshbag Marauder is a good suggestion, but I don't want to drop Reassembling Skeleton for it.

Lightmine Field could go into the deck, but it also hurts myself.

Cheers

I'm surprised Scoured Barrens isn't in here. It's a Karlov trigger for nothing!

Have you considered Unspeakable Symbol? It doesn't have as much untility overall but it can really help buff Karlov, especially with all the lifegain going on.

Bojuka Bog is missing here.

I also run a Karlov deck, and I've noticed you're missing the same thing I was missing...a way to get past chump blockers. I'd add Loxodon Warhammer, Godsend, or something that can give Karlov some type of evasion (flying, unblockable, etc.) Also, if you'd like to throw in one more way to stop people from attacking you, Koskun Falls is a great card. And a cheap way to get automatic counters on Karlov is Orzhov Advokist Just some ideas.

Why do you prefer to use Debtors' Knell instead of Sheoldred, Whispering One? They both cost 7 mana and Sheodred has the added bonus of forcing opponents to sacrifice a creature in their turn. Also, why no Archangel of Thune, Enlightened Tutor, Vindicate, Anguished Unmaking? Kokusho, the Evening Star is also great.