Foundry Inspector

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

Etherium Sculptor

Hardened Scales

If one or more +1/+1 counters would be put on a creature you control, that many plus one +1/+1 counters are put on it instead.

Ugin, the Ineffable

Colorless spells you cast cost {2} less to cast.
+1: Exile the top card of your library face down and look at it. Create a 2/2 colorless Spirit creature token. When that token leaves the battlefield, put the exiled card into your hand.
−3: Destroy target permanent that's one or more colors.

Herald of Kozilek

Devoid (This card has no color.)
Colorless spells you cast cost {1} less to cast.

Hydra's Growth

Enchant creature
When Hydra's Growth enters, put a +1/+1 counter on enchanted creature.
At the beginning of your upkeep, double the number of +1/+1 counters on enchanted creature.

Artificer Class

(Gain the next level as a sorcery to add its ability.)
The first artifact spell you cast each turn costs {1} less to cast.
{1}{U}: Level 2
When this Class becomes level 2, reveal cards from the top of your library until you reveal an artifact card. Put that card into your hand and the rest on the bottom of your library in a random order.
{5}{U}: Level 3
At the beginning of your end step, create a token that's a copy of target artifact you control.

Enthusiastic Mechanaut

Flying
Artifact spells you cast cost {1} less to cast.

Ramos, Dragon Engine

Flying
Whenever you cast a spell, put a +1/+1 counter on Ramos for each of that spell's colors.
Remove five +1/+1 counters from Ramos: Add {W}{W}{U}{U}{B}{B}{R}{R}{G}{G}. Activate only once each turn.

Cloud Key

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

Acolyte of Bahamut

Commander creatures you own have "The first Dragon spell you cast each turn costs {2} less to cast."

Shadow in the Warp

The first creature spell you cast each turn costs {2} less to cast.
Whenever an opponent casts their first noncreature spell each turn, Shadow in the Warp deals 2 damage to that player.