Well, with Tomb and Shaft the obvious answer is FoEE.
Should FoEE worship anyone else first?
I dislike new Nemelex, doesn't even have card tiers.
Doesn't take advantage of the extra inventory space freed by Stasis restrictions.
The FoEE sequence is Kiku -> Fedhas -> Lug -> Nem
But can FoEE risk Miasma surround with Stasis?
Sure, he can just dig away from it, right? Yeah, mandible switching takes no time.
That's a long wait for Nem, though.
Any other species use Nem?
DsAK will go either Nem or Makhleb, depending. Maybe Usk? Nem is the most Invo scaling, though, and the best potential fit for Ds mutation diversity. But inventory pressure.
Gnoll might be good for sniffing dropped decks, back when they dropped? But don't they drop at one's feet? Anyway Gnoll has inventory problem, so this is a bad fit.
Octopode is an interesting choice. Lotsa free inventory due to restrictions. Wants to keep his Necro rather than going Zin. Competes with Jiyva and Ash though. Unsure how well cards synergize with OpVM. Would have to be after Kiku -> Fedhas. (Which is too common a start, surely in need of rebalance.) I can't decide whether Nem should replace Jiyva or Ash.
The pivotal deck is Escape. That determines synergy. FoEE loves that Velocity has Swiftness.
Those are all the candidates.