Starnheim Courser

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

Island

Sol Ring

Starfield Mystic

Enchantment spells you cast cost {1} less to cast.
Whenever an enchantment you control is put into a graveyard from the battlefield, put a +1/+1 counter on Starfield Mystic.

Killian, Ink Duelist

Lifelink
Menace (This creature can't be blocked except by two or more creatures.)
Spells you cast that target a creature cost {2} less to cast.

Swamp

Transcendent Envoy

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

Plains

Hero of Iroas

Aura spells you cast cost {1} less to cast.
Heroic — Whenever you cast a spell that targets Hero of Iroas, put a +1/+1 counter on Hero of Iroas.

Eriette of the Charmed Apple

Each creature that's enchanted by an Aura you control can't attack you or planeswalkers you control.
At the beginning of your end step, each opponent loses X life and you gain X life, where X is the number of Auras you control.

Danitha Capashen, Paragon

First strike, vigilance, lifelink
Aura and Equipment spells you cast cost {1} less to cast.

Helm of Awakening

Sram, Senior Edificer

Whenever you cast an Aura, Equipment, or Vehicle spell, draw a card.

Eriette, the Beguiler

Lifelink
Whenever an Aura you control becomes attached to a nonland permanent an opponent controls with mana value less than or equal to that Aura's mana value, gain control of that permanent for as long as that Aura is attached to it.

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.

Inquisitive Glimmer

Enchantment spells you cast cost {1} less to cast.
Unlock costs you pay cost {1} less.