The Ur-Dragon - 361 M CMM

Eminence — As long as The Ur-Dragon is in the command zone or on the battlefield, other Dragon spells you cast cost {1} less to cast.
Flying
Whenever one or more Dragons you control attack, draw that many cards, then you may put a permanent card from your hand onto the battlefield.

mythic
Legendary Creature — Dragon Avatar
From the Magic: The Gathering set Commander Masters.