Aluren

Any player may cast creature spells with mana value 3 or less without paying their mana costs and as though they had flash.

Darksteel Citadel

Tree of Tales

Great Furnace

Summoner's Egg

Imprint — When Summoner's Egg enters the battlefield, you may exile a card from your hand face down.
When Summoner's Egg dies, turn the exiled card face up. If it's a creature card, put it onto the battlefield under your control.

Grinding Station

{T}, Sacrifice an artifact: Target player mills three cards.
Whenever an artifact enters the battlefield, you may untap Grinding Station.

Pyrite Spellbomb

{R}, Sacrifice Pyrite Spellbomb: It deals 2 damage to any target.
{1}, Sacrifice Pyrite Spellbomb: Draw a card.

Myr Retriever

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

Forest

Mycosynth Golem

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Artifact creature spells you cast have affinity for artifacts. (They cost {1} less to cast for each artifact you control.)

Goblin Welder

{T}: Choose target artifact a player controls and target artifact card in that player's graveyard. If both targets are still legal as this ability resolves, that player simultaneously sacrifices the artifact and returns the artifact card to the battlefield.

Blasting Station

{T}, Sacrifice a creature: Blasting Station deals 1 damage to any target.
Whenever a creature enters the battlefield, you may untap Blasting Station.

Junk Diver

Flying
When Junk Diver dies, return another target artifact card from your graveyard to your hand.

Gamble

Search your library for a card, put that card into your hand, discard a card at random, then shuffle.