Drossforge Bridge

Drossforge Bridge enters tapped.
Indestructible
{T}: Add {B} or {R}.

Goldmire Bridge

Goldmire Bridge enters tapped.
Indestructible
{T}: Add {W} or {B}.

Sacrifice an artifact: Atog gets +2/+2 until end of turn.

Whenever an artifact you control enters, Reckless Fireweaver deals 1 damage to each opponent.

Whenever an artifact enters, you may gain 1 life.

When Myr Sire dies, create a 1/1 colorless Phyrexian Myr artifact creature token.

Whenever an artifact is put into a graveyard from the battlefield, you may have target opponent lose 1 life.

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

Flying
Whenever another artifact you control enters, Glaze Fiend gets +2/+2 until end of turn.

Defender
When Gleaming Barrier dies, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

{T}, Sacrifice an artifact: Orcish Vandal deals 2 damage to any target.

When Perilous Myr dies, it deals 2 damage to any target.

When Filigree Familiar enters, you gain 2 life.
When Filigree Familiar dies, draw a card.

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

Rustvale Bridge enters tapped.
Indestructible
{T}: Add {R} or {W}.