Nightmare Lash and Lashwrithe don't follow my deckbuilding rule. See the first part of the original post.

Kiku, Night's Flower could certainly work, as well as Forced March. I own neither, currently. Kiku might be a good replacement for Stromgald Crusader or Guul Draz Assassin. Forced March is harder. While classic removal, it doesn't necessarily outperform Black Sun's Zenith or Consume the Meek (at least at the 3 CMC level); however, it is better than Consume the Meek at higher CMCs. I'll have to think about that one.
True. It would provide me the ability to essentially double up on that effect (since Pestilence Demon and Massacre Wurm sort of play that role). That being said...I don't know if it would be better than Massacre Wurm or Pestilence Demon, and I also don't know if I need another board wipe effect. I need play more games with the deck and see what happens.

------------------------

In unrelated news, Xenic Poltergeist seems like a great possibility to gain another artifact destruction effect (tangentially, that is) in a deck which is sorely missing these effects.

Yep, was just mentioning them (with the caveat in my recommendation) since sometimes deck-building restrictions need to be flexed

I have made plenty a deck that folds due to not having good support (my Rith deck when she was only myconids and saproling producing cards).

A suggestion to make your recursion shadow dudes stronger, and doubling as a repeatable "fog" - Stronghold Overseer.

Ah, okay. Yeah, this is part of a series of decks for each color, so I'm not bending on deck-building restrictions for anything.
Solid Green Devotion Polukranos
Solid Red Devotion Marton Stromgald

The repeatable fog is nice, but...did my one shadow guy really need to be stronger? Mostly just use him as repeatable sac more than anything.

I'll have to think about the repeatable fog effect. Drana might be a better card for this, although Overseer certainly is a little more classy and underused. Hm...questions, questions...

Updated this deck with some newer and newish cards. I can't recall all of the cards I took out, but the list is updated with these changes:

Ob Nixilis Reignited, Smothering Abomination, Vampiric Rites, Liliana, Heretical Healer, Hythonia the Cruel, Desecration Demon, Drana, Liberator of Malakir, Gravecrawler, and Geralf's Messenger.

I know I took out more than a couple CMC = 5 cards in order to hopefully make that turn more about playing my commander. There was also a number of higher costing cards than that taken out to move the mana curve down so more spells get played more often. I kept finding the deck playing out just one spell a turn and doing mostly nothing. Well, I think this is a little more aggressive.