Dragon

Flying, menace
Whenever this creature deals combat damage to a player, gain control of target artifact that player controls.

The Ur-Dragon

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.

Omniscience

You may cast spells from your hand without paying their mana costs.