I play a version of Nahiri similar to yours but a bit heavier on the creatures. I highly recommend Tatsumasa, the Dragon's Fang. I would also suggest adding three more mana rocks in the 2 cmc category. You really want to have a mana rock out early enough to get Nahiri out turn four or earlier. The sooner she comes out, the more sustainability she'll have, the sooner you'll establish a board presence, the sooner you can blow all the lands and profit. Nahiri allows you to continue to put stuff out on the battlefield without mana which is a game breaker once that Armageddon has resolved. Also, Guardian Idol is excellent in this deck as he serves as ramp or can be activated post wrath effect and get in for beats.
This list is very similar to the one I put together. I feel you could benefit from Winter Orb and Static Orb. Not quite Armageddon or Ravages of War, but seeing as you can't tutor for these cards in mono white, I feel upping the quantity of land disrupt cards will help with consistency. Sort of how you went heavy on various board wipes for consistency. The land disrupt is just as significant as the board wipes in this deck because you can continue to play and equip equipment without using mana where as your opponents will not have the same luxury. I normally wouldn't suggest Luminarch Ascension because it usually only goes off if you get out in the first few turns but with as many wipes as this deck packs, I would consider it's inclusion.
The best card that I think you're missing is Intuition.
While it's a bit pricey, it's insane in my deck
I actually play intuition in my mimeoplasm as well. For some reason I completely spaced on it. Vamp tutor is another one I forgot to mention.
I've won a few games off general damage with a beefy simic sky swallower but with skitz and inkwell in there already he may be choppable. I'd be willing to swap him out. Massacre Wurm is another card I forgot to mention but I'd look at your meta before considering putting him in. He may not be needed where you play. I personally have inflicted much damage and taken out many players with this guy. More of a toolbox creature but can be a finisher.
You should cut the non Sol Ring ramp. It's too slow for a dedicated reanimator deck. Amulet seems a bit slow as well. I'd also say cut green sun's zenith. If you have a mana dork to play on turn 1 that's good but spending 2 on a mana dork that produces 1 mana seems like a bit much and you should be be reanimating the larger targets not spending massive amount of mana on them. I would also consider some 1 mana cantrips. This is essentially a combo deck and they help you reach your pieces (creature, enabler (entomb,buried alive, survival), reanimate spell) Think legacy reanimator. Despite all I've said you do have a solid/focused list. Definitely good enough to draw some early hate at the multiplayer table.
Crib Swap has all creature types so it's recurrable with Horde. Bloom Tender adds 5 mana to pool if Horde is out. Slithermuse will help refill your hand. Green Sun's Zenith is essentially a Bloom Tender tutor. Jarad's Orders will put an elemental in your hand and another in your yard for Horde to put in play later. That's all I have for now but I'll post if I think of anything else.
As mentioned above, Life's Finale is probably the closest thing you'll find to an entomb for opponents but it's obviously a bit inconvenient. For Lasav, I'd reccomend adding draw/discard effects like Windfall, Jace's Archivist, Whispering Madness, etc. Mesmeric orb, Traumatize, and Glimpse the Unthinkable are good as well.
I actually play intuition in my mimeoplasm as well. For some reason I completely spaced on it. Vamp tutor is another one I forgot to mention.
I've won a few games off general damage with a beefy simic sky swallower but with skitz and inkwell in there already he may be choppable. I'd be willing to swap him out.
Massacre Wurm is another card I forgot to mention but I'd look at your meta before considering putting him in. He may not be needed where you play. I personally have inflicted much damage and taken out many players with this guy. More of a toolbox creature but can be a finisher.
You should cut the non Sol Ring ramp. It's too slow for a dedicated reanimator deck. Amulet seems a bit slow as well. I'd also say cut green sun's zenith. If you have a mana dork to play on turn 1 that's good but spending 2 on a mana dork that produces 1 mana seems like a bit much and you should be be reanimating the larger targets not spending massive amount of mana on them. I would also consider some 1 mana cantrips. This is essentially a combo deck and they help you reach your pieces (creature, enabler (entomb,buried alive, survival), reanimate spell) Think legacy reanimator. Despite all I've said you do have a solid/focused list. Definitely good enough to draw some early hate at the multiplayer table.