I tried out the Sejiri Steppe tech in the past and really didn't like it.
Here's why:
1) If you don't have Maze out, it means you can't attack with your Knights without risking removal.
2) If you do have Maze out, they can just kill your Knight in response to your Maze activation.
3) It messes with your manabase. We're already running Karakas, Wastelands, sometimes Maze, sometimes Dryad Arbor, sometimes Bojuka Bog - another ETB tapped land that produces only white continues to strain what is already a pretty stressed manabase.
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Here's a Dark Maverick / Junk list I've been idly playing around with:
// Lands
4 [ZEN] Verdant Catacombs
2 [U] Bayou
3 [B] Scrubland
1 [5E] Swamp (1)
2 [R] Savannah
3 [MPR] Wasteland
1 [LG] Karakas
2 [ON] Windswept Heath
1 [M13] Forest (3)
2 [ZEN] Marsh Flats
1 [FUT] Dryad Arbor
// Creatures
4 [RTR] Deathrite Shaman
4 [RAV] Dark Confidant
3 [FUT] Tarmogoyf
3 [CFX] Knight of the Reliquary
3 [FNM] Mother of Runes
1 [LRW] Gaddock Teeg
// Spells
4 [LRW] Thoughtseize
2 [BOK] Umezawa's Jitte
4 [RTR] Abrupt Decay
3 [CST] Swords to Plowshares
3 [V09] Sensei's Divining Top
2 [MBS] Green Sun's Zenith
2 [FE] Hymn to Tourach (4)
Testing has been showing that it's... weird. We all know Mom is amazing if you draw her early. Sometimes the deck is awesome and you get Mom + beater out, but sometimes you get the other hands/draws where you lose your beaters to removal THEN draw your Moms.