Gravestone Strider

{1}: Add one mana of any color. Activate only once each turn.
{2}, Exile Gravestone Strider from your graveyard: Exile target card from a graveyard.

Hedron Archive

{T}: Add {C}{C}.
{2}, {T}, Sacrifice this artifact: Draw two cards.

Snow-Covered Wastes

Bronze Walrus

When Bronze Walrus enters, scry 2. (Look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)
{T}: Add one mana of any color.

Hedron Crawler

{T}: Add {C}. ({C} represents colorless mana.)

Manakin

Hedron Blade

Equipped creature gets +1/+1.
Whenever equipped creature becomes blocked by one or more colorless creatures, it gains deathtouch until end of turn. (Any amount of damage it deals to a creature is enough to destroy it.)
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Endless One

Endless One enters with X +1/+1 counters on it.

Cryptic Trilobite

Cryptic Trilobite enters with X +1/+1 counters on it.
Remove a +1/+1 counter from Cryptic Trilobite: Add {C}{C}. Spend this mana only to activate abilities.
{1}, {T}: Put a +1/+1 counter on Cryptic Trilobite.

Oasis Gardener

When Oasis Gardener enters, you gain 2 life.
{T}: Add one mana of any color.

Alloy Myr

Hedron Scrabbler

Landfall — Whenever a land you control enters, Hedron Scrabbler gets +1/+1 until end of turn.

Millikin

{T}, Mill a card: Add {C}. (To mill a card, put the top card of your library into your graveyard.)