Dwarven Siege Engineer

Scrapper (When this creature enters the battlefield,
return target artifact card with lesser converted mana
cost from your graveyard to your hand.)
Whenever an artifact you control is put into a graveyard, you get {e}.
Pay any amount of {e}: Return a vehicle or equip-
ment card from your graveyard to your hand with converted mana cost equal to the amount of {e} spent.