I don't think you can do anything about graveyard hate; does that mean you need to be able to wage a stronger ground war?
The only graveyard hate I've been unable to do anything about is Stonecloaker, but I hesitate to tweak the whole deck to deal with that one card. If multiple people are packing enough graveyard hate or if one person weirdly commits to it, then I probably just lose. Otherwise, graveyard hate is generally something one-shot (like Bojuka Bog, which I can recover from) or something that sits on the board (like Leyline of the Void, which I can blow up with Qasali Pridemage or something). Obviously graveyard hate is a problem for a deck like this, but it's not completely insurmountable.
In what other areas do you think the deck is lacking?
None? I mean, I've looked at other Karador-based Commander decks and I think that mine is totally the best one out there. I do want to make a few more refinements, but I've come reasonably close to pushing the whole concept of a dedicated dredge deck in Commander as far as it'll go.
Sidisi seems like he'd synergize well, especially if he can be fit into a reanimation combo of some sort.
Sidisi is a lady. A snake lady. As for synergies, she'd be bonkers. At a minimum, Karador turns her into a reusable tutor for five mana.
Not sure how Kytheon fits?
Notably, planeswalkers are pretty lackluster in this deck. I've had several suggestions for including this planeswalker or that one, and people just don't seem to realize that those cards are probably just going to get dredged away and sit in my graveyard all game. However, the new
Magic Origins planeswalkers change that. I can pull them from my graveyard as creatures, then possibly flip them. They're tricky to evaluate, because they provide a lot of potential value for a cheap initial investment, but no one thing that they do is so amazing that it is game-breaking. Three of these guys fit into my colors, and I'm not sure about any of them. In Kytheon's case...
-He's a one-drop, potentially indestructible blocker. As an actual first turn one-drop, he'd not be very compelling, but one-drops are nice with Karador because I can throw one on the board while using the rest of my mana for the turn on something more important.
-Once I can afford to start swinging at people, he gets in easily and transforms.
-His +2 can kill an annoying creature by forcing it to into my lethal blockers.
-His +1 is just downright good.
-His 0 wouldn't matter much, but would let him turn into a creature to be sacrificed to something in a pinch.
-Once he inevitably dies, he's a one-drop creature in my graveyard, which is fodder for all sorts of things in this deck.
No single one of those factors is enough to devote a slot to him. On the other hand, in ideal situations where all of those aspects see use in the same game, he'd be extremely potent. Reality is somewhere in between. I'm leaning toward not devoting a slot to Kytheon, but I do think he and the other Origins walkers are really tough to evaluate.
Dromoka is a solid beater with Lifelink (invaluable in free for all) and a sweet controlling effect.
Yeah, the question there is whether the anti-disruption ability is sweet enough to take a slot in this deck. I can get bigger bodies and I can get better lifegain, but having all of those things in the same package just might be worth it.
False Prophet is a friend to anyone who's okay with wiping the board, but obviously he'd need to survive the turn after he's played. I used to run him in my Enchantment deck when it had less creatures, and allow my opponents to bet big at the start of the game when I knew I had a slower hand, and then drop FP to gut them.
He doesn't have to survive. This is more like a Wrath of God option for a deck that eschews sorceries because they're hard to cast from the graveyard. I hesitate to run this card if I don't increase the number of sacrifice outlets, but the idea is to sac my whole army to an outlet, sac False Prophet, and then (with Prophet's ability on the stack), sac my outlet to itself. My opponent's creatures all go away. So do mine, but they're safely in my graveyard,
a place from which I can summon them because that's what my whole deck is about.