I like the effect from the Lamia, and a 4/4 lifelink has been relevant on occasion, but spending 5 mana for the effect just feels bad, and it's rare that I want to bring it back with Create Undead. The deck doesn't really take advantage of the cost reduction for casting spells from the graveyard, either, so overall I've just not been super happy with it. Solitude comes in as another piece of removal. The ability to flash it in may be relevant, and the possibility (though slim) of casting it for free is super good. It did, in fact, make an appearance in the first game after I added it, and made a huge impact: one player brought a stronger deck to the table than anyone else, and started very fast. I ended up exiling Sun Titan(!!!) to put the brakes on a little bit, and it ended up being super relevant that I did.
Oriq Loremage for Buried Alive or Entomb. Oriq is slow, needing to tap, isn't a good reanimation target because of that, and I've felt kind of bad the few games where I've had it online. If the deck is already chugging along, taking the time to tutor up a reanimation target every turn is time consuming and a little obnoxious. On the other hand, doing it once, for high impact, is a little more palatable, I think. The real choice is between the ability to assemble a combo in the graveyard (and do I want to have that ability, since it will ratchet up the power level significantly), or the versatility of the instant speed effect?
Also strongly considering pulling Yawgmoth, Thran Physician from another deck to bring in here, but I'm not sure what I would cut for it yet. The deck could definitely use another 1-3 sac outlets, and having some additional card draw is welcome for when the deck isn't quite chugging along. The fact that it is also removal, and ALSO a discard outlet makes it even more of a powerhouse here than it is in other decks. Just not sure who loses: Marchesa, The Black Rose, Meren, of Clan Nel Toth, or Tymna, the Weaver.
Additionally, I'm thinking the deck could really use one mass reanimation spell. Living Death is likely the best option, as it also serves as a board wipe, and it's one of the lowest CMC options for the effect, but I may want to look at something more one-sided. This would likely take the place of Grimoire of the Dead . I like the idea of the card, but it's slow, expensive, and highly telegraphed. Every time I've drawn it, I've groaned. For now, I'm slotting in Master of Death to try it out.
Fellwar for Dimir Signet is due to having a game recently where Fellwar wasn't making the colors I needed, and feeling like a Signet is more likely to get me where I need to be. We'll see...