It's interesting that we got both of these in mana dork form before we ever got them in land form: Quirion Explorer and Harvester Druid. Although both of those did come out during a period where Wizards was very averse to printing good multicolor lands, so maybe that makes sense.

Dark Rewards -
Enchantment
At the beginning of your upkeep, if you control a permanent with in its cost, each opponent loses 1 life and you gain 1 life.


Wild Patriot -
Creature - Centaur
~ enters the battlefield with a +1/+1 counter on it if you control a permanent with in its cost.
3/3

Hail a Cab
Sorcery (R)
Search your library for a Vehicle card, put that card onto the battlefield, then shuffle.

EDIT1: I came up with another just now.
EDIT2: Edited overall flavor.

Revoke Plans -
Sorcery
Discard your hand, then draw seven cards.


Revoke Development -
Sorcery
Destroy all artifacts and enchantments your opponents control.

Wither -
Sorcery
Target player reveals hand, discards all land cards.

Meditation
Instant (C)
Gain X life. Draw a card.

Surprised that the second sentence hasn't been printed on a card before.

Master Interceptor —
Creature — Human Soldier (U)
2/4
Master Interceptor can block attacking creatures as though they had no abilities.
Melvon had tried every entrance known and secret, each air vent, even climbed through the dankest of toilets, and yet every infiltration attempt was foiled by same guard with the star tattoo.

I've used this as a keyword for a number of obscure custom environments, calling it "Awareness". My wording for the keyword's reminder text has been "Effects that say this creature can't block another creature don't apply" but I'm not sure if it's any more or less proper + that's for reminder text that has more leeway.

Random-ish singleton design always work I suppose albeit can be rather disappointing or even wasteful. It's pretty weird overall and very defensive - if used as a keyword, which is prolly generally unadvised, it needs to be paired with equally weird / numerous evasion. Evasive creatures are obviously important for breaking stalled boards which this can negate, especially in higher numbers.

You could make it work like Trap Runner if the rules have trouble ignoring abilities.

Curse of Doom

Enchantment -- Aura Curse
Enchant player
At the beginning of enchanted player's upkeep, put a doom counter on Curse of Doom. Then, if there are thirteen or more doom counters on Curse of Doom, enchanted player loses the game.

Super exciting card I know - you can thank me later. Somewhere between Catacomb Slug, Catacomb Crocodile, and Rotting Mastodon. Creatures with the stats 2/7 are pretty rare as is, there's only 7 of them in-game - none of which are vanilla.

Brain Dump
Land
Brain Dump enters the battlefield with a charge counter on it.
: Add .
, Remove a charge counter from Brain Dump: Draw a card.

This is to Ponder what Serum Visions is to Preordain.

A cantripping Act of Treason. Currently closest to that looks to be Bloody Betrayal.

Comparable to Aphetto Dredging and Urborg Uprising.