For a long time I though they would never print such cycle. But I guess, they are fine with tapped lands. They won't disrupt any format because they can't enter untapped.
Diamond 1
Land
As this enters the battlefield, you may pay 1 life and exile a basic land from your hand. If you don't, this enters the battlefield tapped. T: Add W, U or B.
Diamond 2
Land
As this enters the battlefield, you may exile a basic land from your hand. If you don't, this enters the battlefield tapped. T: Add W, U or B. You lose 1 life unless you control a permanent of any color.
It's not a conspiracy theory. The design space between a dual and a land that produces any color is so narrow that I think that filling it with many cycles of trilands may end up making it too easy to build multicolored decks. The full cycles of fetches already does that.
Prison of Defectors
Land T: Add C. T, Pay 1 life: Add one mana of any color. Activate this ability only during another player's turn.
Portal of Freedom
Land
Portal of Freedom enters the battlefield tapped.
When Portal of Freedom enters the battlefield, sacrifice it unless you sacrifice a basic land. T: Add two mana in any combination of colors.
Reveal Multicolor Dual
Land
As Reveal Multicolor Dual enters the battlefield, you may reveal a multicolored card from your hand. If you don't, Reveal Multicolor Dual enters the battlefield tapped. T: Add W or U.
Forgotten Graveyard
Land T: Add C. T: Choose a color of a creature or planeswalker card in your graveyard. Add one mana of that color.
Personally I prefer the verbs Shred or Grind.
Blessed Coast (DFC front)
Land (Uncommon)
enters tapped
When this enters the battlefield you gain 1 life.
T: Add W or U.
Blessed Ravine (DFC back)
Land (Uncommon)
enters tapped
When this enters the battlefield you gain 1 life.
T: Add W or G.
Land
T: Add C.
W, T: Add WU, WB, WG or WR.
Counter target spell if all lands of its controller are tapped.
Diamond 1
Land
As this enters the battlefield, you may pay 1 life and exile a basic land from your hand. If you don't, this enters the battlefield tapped.
T: Add W, U or B.
Diamond 2
Land
As this enters the battlefield, you may exile a basic land from your hand. If you don't, this enters the battlefield tapped.
T: Add W, U or B. You lose 1 life unless you control a permanent of any color.
Prison of Defectors
Land
T: Add C.
T, Pay 1 life: Add one mana of any color. Activate this ability only during another player's turn.
Portal of Freedom
Land
Portal of Freedom enters the battlefield tapped.
When Portal of Freedom enters the battlefield, sacrifice it unless you sacrifice a basic land.
T: Add two mana in any combination of colors.
Reveal Multicolor Dual
Land
As Reveal Multicolor Dual enters the battlefield, you may reveal a multicolored card from your hand. If you don't, Reveal Multicolor Dual enters the battlefield tapped.
T: Add W or U.
Forgotten Graveyard
Land
T: Add C.
T: Choose a color of a creature or planeswalker card in your graveyard. Add one mana of that color.