// Lands
3 [AQ] Mishra's Factory (4)
3 [TE] Ancient Tomb
1 [NE] Kor Haven
3 [TE] Wasteland
4 [EX] City of Traitors
4 [TSP] Flagstones of Trokair
8 [4E] Plains (1)

// Creatures
3 [ALA] Elspeth, Knight-Errant

// Spells
4 [LG] Moat
4 [SH] Mox Diamond
3 [TE] Humility
2 [LRW] Oblivion Ring
4 [MR] Chalice of the Void
3 [DS] Trinisphere
4 [FD] Crucible of Worlds
3 [b] Armageddon
4 [US] Smokestack

// Sideboard
SB: 2 [LRW] Oblivion Ring
SB: 2 [REW] Powder Keg
SB: 3 [OD] Sphere of Law
SB: 3 [UL] Defense Grid
SB: 2 [5E] Wrath of God
SB: 3 [WL] Null Rod
I thought 2 Oblivion Ring was retarded.

Anyway, Ancient Tomb, like Crucible, should be an undisputed 4-of. It's the best land next to Flagstones. Maybe you should a Factory since you run Moat anyway.

Other than that, I can't argue against your numbers. Armageddon is what makes the deck, but perhaps times have changed. I always ran 5 Geddon or Ravage of War. But since you're running Elspeth and the gang, the Armageddon route might not be Stax's number 1 goal anymore. 4 Smokestack should be correct, since you have Elspeth and you have more perms available in extra Moat/Humility.

Have you tried Horizon Canopy? I run a singleton. Needless to say, it's an engine with Crucible of Worlds.

If you wanna go crazy and try interesting cards, awhile back I suggested trying out Beseech the Queen. Pretty left field, huh? I thought of using it because it can fetch Crucible/Armageddon when you're in a stalemate. Plus, it can fetch utility land. Just throwing it out there.

Bottled Cloister is another sb option.