Workshop Assistant

When Workshop Assistant dies, return another target artifact card from your graveyard to your hand.

Myr Retriever

When Myr Retriever dies, return another target artifact card from your graveyard to your hand.

Great Furnace

Darksteel Citadel

Vault of Whispers

Scrap Trawler

Whenever Scrap Trawler or another artifact you control is put into a graveyard from the battlefield, return to your hand target artifact card in your graveyard with lesser mana value.

Dutiful Attendant

When Dutiful Attendant dies, return another target creature card from your graveyard to your hand.

Cadaver Imp

Flying
When Cadaver Imp enters, you may return target creature card from your graveyard to your hand.