MANAHIVE

Equivalent cards to “Salt Flats” would be other lands with the same color identity ({W}{B}), that enter tapped, can tap for either white or black, and deal 1 damage to you when tapped for colored mana. Here are some:

• “Caves of Koilos”

  • Type: Land
  • {T}: Add {C}.
  • {T}: Add {W} or {B}. “Caves of Koilos” deals 1 damage to you.

• “Tainted Field”

  • Similar, but only taps for colored if you control a Swamp.

• “Fetid Heath”

  • Similar, but uses filter mechanic, does not deal damage.

So, “Caves of Koilos” is the direct equivalent. The reason: It matches the color identity, mana ability, and the life-loss clause.