Manamorphose

Add two mana in any combination of colors.
Draw a card.

Blood Celebrant

{B}, Pay 1 life: Add one mana of any color.

Stormscape Familiar

Flying
White spells and black spells you cast cost {1} less to cast.

Lab Rats

Buyback {4} (You may pay an additional {4} as you cast this spell. If you do, put this card into your hand as it resolves.)
Create a 1/1 black Rat creature token.

Carrion Feeder

Carrion Feeder can't block.
Sacrifice a creature: Put a +1/+1 counter on Carrion Feeder.

Orochi Leafcaller

Sprout Swarm

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.)
Buyback {3} (You may pay an additional {3} as you cast this spell. If you do, put this card into your hand as it resolves.)
Create a 1/1 green Saproling creature token.

Naiad of Hidden Coves

During turns other than yours, spells you cast cost {1} less to cast.

Capsize

Buyback {3} (You may pay an additional {3} as you cast this spell. If you do, put this card into your hand as it resolves.)
Return target permanent to its owner's hand.

Lampad of Death's Vigil

{1}, Sacrifice a creature: Each opponent loses 1 life and you gain 1 life.

Goblin Electromancer

Instant and sorcery spells you cast cost {1} less to cast.

Dark Ritual

Whispers of the Muse

Buyback {5} (You may pay an additional {5} as you cast this spell. If you do, put this card into your hand as it resolves.)
Draw a card.

Cabal Ritual

Add {B}{B}{B}.
Threshold — Add {B}{B}{B}{B}{B} instead if seven or more cards are in your graveyard.

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}.

Signpost Scarecrow

Vigilance
{2}: Add one mana of any color.

Blood Bairn

Sacrifice another creature: Blood Bairn gets +2/+2 until end of turn.

Thornscape Familiar

Red spells and white spells you cast cost {1} less to cast.

Tinder Wall

Defender (This creature can't attack.)
Sacrifice Tinder Wall: Add {R}{R}.
{R}, Sacrifice Tinder Wall: It deals 2 damage to target creature it's blocking.

Nightscape Familiar

Blue spells and red spells you cast cost {1} less to cast.
{1}{B}: Regenerate Nightscape Familiar.

Stonework Packbeast

Stonework Packbeast is also a Cleric, Rogue, Warrior, and Wizard.
{2}: Add one mana of any color.

Wild Cantor

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

Rite of Flame

Add {R}{R}, then add {R} for each card named Rite of Flame in each graveyard.

Lotus Petal

{T}, Sacrifice Lotus Petal: Add one mana of any color.

Thunderscape Familiar

First strike
Black spells and green spells you cast cost {1} less to cast.

Viscera Seer

Sacrifice a creature: Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Abundant Growth

Enchant land
When Abundant Growth enters, draw a card.
Enchanted land has "{T}: Add one mana of any color."

Utopia Sprawl

Enchant Forest
As Utopia Sprawl enters, choose a color.
Whenever enchanted Forest is tapped for mana, its controller adds an additional one mana of the chosen color.

Bloodthrone Vampire

Sacrifice a creature: Bloodthrone Vampire gets +2/+2 until end of turn.

Mortician Beetle

Whenever a player sacrifices a creature, you may put a +1/+1 counter on Mortician Beetle.