Dragonlord's Servant

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

Rivaz of the Claw

Menace
{T}: Add two mana in any combination of colors. Spend this mana only to cast Dragon creature spells.
Once during each of your turns, you may cast a Dragon creature spell from your graveyard.
Whenever you cast a Dragon creature spell from your graveyard, it gains "When this creature dies, exile it."

Dragonspeaker Shaman

Dragon spells you cast cost {2} less to cast.