Emerald Medallion

Green spells you cast cost {1} less to cast.

Sapphire Medallion

Blue spells you cast cost {1} less to cast.

Myth Unbound

Your commander costs {1} less to cast for each time it's been cast from the command zone this game.
Whenever your commander is put into the command zone from anywhere, draw a card.

Cloud Key

As this artifact enters, choose artifact, creature, enchantment, instant, or sorcery.
Spells you cast of the chosen type cost {1} less to cast.

Murkfiend Liege

Other green creatures you control get +1/+1.
Other blue creatures you control get +1/+1.
Untap all green and/or blue creatures you control during each other player's untap step.

Defiler of Vigor

Trample
As an additional cost to cast green permanent spells, you may pay 2 life. Those spells cost {G} less to cast if you paid life this way. This effect reduces only the amount of green mana you pay.
Whenever you cast a green permanent spell, put a +1/+1 counter on each creature you control.

Insight

Whenever an opponent casts a green spell, you draw a card.

Seal of the Guildpact

As this artifact enters, choose two colors.
Each spell you cast costs {1} less to cast for each of the chosen colors it is.

Nylea, Keen-Eyed

Indestructible
As long as your devotion to green is less than five, Nylea isn't a creature.
Creature spells you cast cost {1} less to cast.
{2}{G}: Reveal the top card of your library. If it's a creature card, put it into your hand. Otherwise, you may put it into your graveyard.

Homarid Spawning Bed

{1}{U}{U}, Sacrifice a blue creature: Create X 1/1 blue Camarid creature tokens, where X is the sacrificed creature's mana value.

Kefnet's Monument

Blue creature spells you cast cost {1} less to cast.
Whenever you cast a creature spell, target creature an opponent controls doesn't untap during its controller's next untap step.

Yeva, Nature's Herald

Flash (You may cast this spell any time you could cast an instant.)
You may cast green creature spells as though they had flash.

Centaur Omenreader

As long as this creature is tapped, creature spells you cast cost {2} less to cast.

Fable of Wolf and Owl

Whenever you cast a green spell, you may create a 2/2 green Wolf creature token.
Whenever you cast a blue spell, you may create a 1/1 blue Bird creature token with flying.

Paragon of Gathering Mists

Other blue creatures you control get +1/+1.
{U}, {T}: Another target blue creature you control gains flying until end of turn.

Ivy Lane Denizen

Whenever another green creature you control enters, put a +1/+1 counter on target creature.

Rhonas's Monument

Green creature spells you cast cost {1} less to cast.
Whenever you cast a creature spell, target creature you control gets +2/+2 and gains trample until end of turn.

Momir Vig, Simic Visionary

Whenever you cast a green creature spell, you may search your library for a creature card, reveal it, then shuffle and put that card on top.
Whenever you cast a blue creature spell, reveal the top card of your library. If it's a creature card, put that card into your hand.