Undermountain Adventurer

Vigilance
When Undermountain Adventurer enters, you take the initiative.
{T}: Add {G}{G}. If you've completed a dungeon, add six {G} instead.

Reckless Barbarian

Sacrifice Reckless Barbarian: Add {R}{R}.

Reclusive Taxidermist

Reclusive Taxidermist gets +3/+2 as long as there are four or more creature cards in your graveyard.
{T}: Add one mana of any color.

Meteor Golem

When this creature enters, destroy target nonland permanent an opponent controls.

Chaos Maw

When Chaos Maw enters, it deals 3 damage to each other creature.

Orochi Leafcaller

Wirewood Elf

Orochi Merge-Keeper

{T}: Add {G}.
As long as Orochi Merge-Keeper is modified, it has "{T}: Add {G}{G}." (Equipment, Auras you control, and counters are modifications.)

Sakura-Tribe Springcaller

At the beginning of your upkeep, add {G}. Until end of turn, you don't lose this mana as steps and phases end.

Ancient Bronze Dragon

Flying
Whenever Ancient Bronze Dragon deals combat damage to a player, roll a d20. When you do, put X +1/+1 counters on each of up to two target creatures, where X is the result.

Llanowar Elves

Axebane Guardian

Defender
{T}: Add X mana in any combination of colors, where X is the number of creatures you control with defender.

Goldhound

First strike
Menace (This creature can't be blocked except by two or more creatures.)
{T}, Sacrifice Goldhound: Add one mana of any color.

Raggadragga, Goreguts Boss

Each creature you control with a mana ability gets +2/+2.
Whenever a creature you control with a mana ability attacks, untap it.
Whenever you cast a spell, if at least seven mana was spent to cast it, untap target creature. It gets +7/+7 and gains trample until end of turn.

Wild Cantor

({R/G} can be paid with either {R} or {G}.)
Sacrifice Wild Cantor: Add one mana of any color.

Generator Servant

{T}, Sacrifice Generator Servant: Add {C}{C}. If that mana is spent on a creature spell, it gains haste until end of turn. (That creature can attack and {T} as soon as it comes under your control.)

Brass's Bounty

For each land you control, create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

Automated Artificer

{T}: Add {C}. Spend this mana only to activate an ability or cast an artifact spell.

Terastodon

When Terastodon enters, you may destroy up to three target noncreature permanents. For each permanent put into a graveyard this way, its controller creates a 3/3 green Elephant creature token.

Verdant Eidolon

{G}, Sacrifice Verdant Eidolon: Add three mana of any one color.
Whenever you cast a multicolored spell, you may return Verdant Eidolon from your graveyard to your hand.

Earthquake Dragon

This spell costs {X} less to cast, where X is the total mana value of Dragons you control.
Flying, trample
{2}{G}, Sacrifice a land: Return Earthquake Dragon from your graveyard to your hand.

Copper Myr

Seasonal Ritual

Add one mana of any color. (Then exile this card. You may cast the creature later from exile.)

Rosethorn Acolyte

Rosethorn Acolyte // Seasonal Ritual

Citanul Stalwart

{T}, Tap an untapped artifact or creature you control: Add one mana of any color.

Sylvan Awakening

Until your next turn, all lands you control become 2/2 Elemental creatures with reach, indestructible, and haste. They're still lands.

Rift Sower

{T}: Add one mana of any color.
Suspend 2—{G} (Rather than cast this card from your hand, you may pay {G} and exile it with two time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost. It has haste.)

Nest Invader

When Nest Invader enters, create a 0/1 colorless Eldrazi Spawn creature token. It has "Sacrifice this creature: Add {C}."

Werebear

{T}: Add {G}.
Threshold — Werebear gets +3/+3 as long as seven or more cards are in your graveyard.

Vine Trellis

Defender (This creature can't attack.)
{T}: Add {G}.

Zhur-Taa Druid

{T}: Add {G}.
Whenever you tap Zhur-Taa Druid for mana, it deals 1 damage to each opponent.

Birchlore Rangers

Tap two untapped Elves you control: Add one mana of any color.
Morph {G} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Yavimaya Sojourner

Domain — This spell costs {1} less to cast for each basic land type among lands you control.

Oasis Ritualist

{T}: Add one mana of any color.
{T}, Exert Oasis Ritualist: Add two mana of any one color. (An exerted creature won't untap during your next untap step.)

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.

Quirion Elves

As Quirion Elves enters, choose a color.
{T}: Add {G}.
{T}: Add one mana of the chosen color.

Thermopod

{S}: Thermopod gains haste until end of turn. ({S} can be paid with one mana from a snow source.)
Sacrifice a creature: Add {R}.

Gargadon

Trample
Suspend 4—{1}{R} (Rather than cast this card from your hand, you may pay {1}{R} and exile it with four time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost. It has haste.)

Ancient Imperiosaur

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Trample, ward {2}
Ancient Imperiosaur enters with two +1/+1 counters on it for each creature that convoked it.

Silhana Starfletcher

Reach (This creature can block creatures with flying.)
As Silhana Starfletcher enters, choose a color.
{T}: Add one mana of the chosen color.