15 creatures is low. Run at least 20.

Burnished Hart and Solemn Simulacrum offer ramp.

Grand Abolisher keeps your turns free from shenanigans.

Weathered Wayfarer keeps you from falling behind on mana. Can fetch nonbasics.

Windborn Muse stalls your opponents' creatures.

Fireshrieker offers double strike.

The Kaldra set are good Equipment.

Caged Sun doubles your White mana and pumps Kemba's army.

Expedition Map is a great land tutor.

Leonin Sun Standard pumps Kemba's army. Great mana sink.

Sculpting Steel is an artifact clone. Copy their Swords!

Spear of Heliod pumps Kemba's army and deters attackers.

Mana rocks for additional ramp can't hurt. Everflowing Chalice is a great mana rock that scales well as games progress. Mind Stone and be popped for a card when it's no longer needed. Sol Ring can be found in the new Commander Precons if you plan on buying one.

Ghostly Prison stalls your opponents' creatures.

Karmic Justice makes your opponents' noncreature removal hurt.

Prison Term is better than Arrest .

One sweeper isn't enough. Run at least four. Austere Command is a Swiss Army Knife Sweeper. Day of Judgment and Wrath of God are low mana options for creature sweepers. Divine Reckoning works well as long as your meta doesn't have too many other Voltron decks. Terminus tucks the board.

Remember the Fallen is a great 2-for-1 recursion spell.

Oblation can tuck Planeswalkers and Commanders.

40 land is a bit high. You can drop a few for space.

Emeria, The Sky Ruin is a powerful creature recursion engine.

Kor Haven and Mystifying Maze deter attackers.

Mikokoro, Center of the Sea offers card draw.

Rogue's Passage makes Kemba unblockable.

Thank you for the suggestions! Very well written. I hadn't realized Oblation could target Planeswalkers! (I learned the game back before they were a thing to think about, and I forget about them a lot.)

I own a couple of the things you mentioned, but they are currently in other decks (particularly, Weathered Wayfarer , Expedition Map and Rogue's Passage ) I will prioritize some other things here.

I hadn't played Terminus because the deck is so reliant on Kemba and I worry about tucking her without a way to fetch her back. I had seen Day of Judgment but thought it was "weak"- maybe I'm spoiled for having had so much experience with Wrath of God from the old days. Well! The price is right for it!

I'll slowly bleed a couple of these into the deck and see where it ends up. Thank you again!

Under consideration from the C14 decks:

Nahiri, the Lithomancer
White Sun's Zenith
Skullclamp
Sol Ring
Assault Suit
Masterwork of Ingenuity

Hi nobu_the_bard, good build +1 from me, i suggest you Stoneforge Mystic there may be a reason if it is banned in modern, with it i think you can add asealy Sword of Feast and Famine and Umezawa's Jitte, REALY GOOD EQUIPENT. There are few mono-white deck, true, but if you replace the Plains with Snow-Covered Plains only you will take advantage of Extraplanar Lens, if you do there is Scrying Sheets to dig the deck.

I appreciate the suggestions DVLuca.

I haven't tried Stoneforge Mystic or any of the Swords of X and Y or Umezawa's Jitte because of the costs ($15 at the cheapest I think for those). Stonehewer Giant was about as far in this direction as I was willing to go. Some of my equipment may appear more expensive now, such as Darksteel Plate, but I had obtained most of them when they were no more than $3.

I know about Snow-Covered Plains and their interaction with Extraplanar Lens, but I have retained the current functioning partly for cost (it'd cost me about $10-$20 to replace all of the plains) but also because my local meta kind of considers it a bit of an extreme optimization. I wasn't aware of Scrying Sheets though, which is an interesting use outside of the Lens.

Thanks nobu_the_bard, did you know of Hanna's Custody??

A fair suggestion DVLuca, but Hanna's Custody doesn't solve any of my main weaknesses. I am less concerned about spot removal against my artifacts compared to say, Vandalblast or Bane of Progress. There are two creatures that provide this function, Leonin Abunas and Indomitable Archangel (also formerly Fountain Watch), but they have the advantage of also being fighters if their protection abilities prove irrelevant; one flies and the other matches Brimaz's tribe.

Something like Darksteel Reactor would mitigate problems arising from my reliance on artifacts, but it does so at the cost of having me spend a lot of resources protecting my tools instead of my threats; it was removed in a far earlier stage of the deck.

Also, the deck has most of its enchantments removed (only Spear of Heliod remains) in an attempt to minimize the sort of impact large-scale enchantment destruction inflicts.

Your comment reinforces that I need to take the time to provide an updated note for this deck to better set down what I am attempting to do and why. Thanks!

nobu_the_bard those two cards that you mentioned dont resolve the problem of the mass-removal cards like Vandalblast or Bane of Progress, those dont target permanent. I suggested you Hanna's Custody becouse is a non-creature permanent. The only solution to the mass-removal i dont remember anythink other Second Sunrise and Faith's Reward but these are cards "no thanks".....

@DVLuca: Yes I know they don't solve it perfectly either. They're still in the deck because they serve dual roles. Indomitable Archangel is a good-sized flyer; Leonin Abunas is a Cat (he benefits from tribal effects, though it seems the only remaining one may be Konda's Banner). Fountain Watch got cut because he didn't have a good secondary function anymore and cost more than either of those two.

I did try Second Sunrise and Faith's Reward but they required me to sit on too much mana for defensive use.