Orzhov Kaya (Oathbreaker)

I usually play EDH... used to play vintage but haven't touched that in like a year. This is my first Oathbreaker deck.

It will be based on Kaya, Orzhov Userper and probably The Elder Spell (but open to ideas). My thought was to cast Kaya, destroy the enemy Oathbreakers, and blast her -5 out of the gate, and hopefully use Kaya's ghost form to keep her on the battlefield if mana allows.

Hoping to stave off opponents with a few deathtouch and/or flying creatures, while slowly dripping on their health and adding to my own and finish them with Kaya.

I plan to use exile based board wipes to disrupt my opponents and fill purgatory to the brim with their vile disgusting creatures so I can fire off my Oathbreaker's -5 and smash.

Concerns I have:
-I like having cards like 'Arrest' that nullify a commander, which is what i'm used to playing however I'm feeling like I should replace it for Oathbreaker. I threw in Sorcerous Spyglass for the same reason, in the hopes it will be effective against their Oathbreaker and jam up their strategy.
-I went for low cost creatures, however if the game extends I don't see how I'd draw cards
-Ok, I probably got greedy and skimped on mana so I could cram other stuff in there. Please talk me out of this.

I would like some ideas on how to improve. Please share your ideas! Thanks.

Notes:
-I do have more non-basic lands to throw in, some of the better ones, but I didn't feel like punching them all in to Deckstats
-I made this deck mostly with what I have on hand... purchased the rest in it's present state and I spent like 10 bucks on card kingdom. I would spend maybe another 5-10 dollars on this deck at most.
-I usually play games with two or three opponents. Rarely 1 on 1.
-I realize Smothering Tithe isn't a mana rock. Who cares.