Towashi Songshaper

Whenever another artifact you control enters, Towashi Songshaper gets +1/+0 until end of turn.

Galvanic Blast

Galvanic Blast deals 2 damage to any target.
Metalcraft — Galvanic Blast deals 4 damage instead if you control three or more artifacts.

Great Furnace

Experimental Synthesizer

When Experimental Synthesizer enters or leaves the battlefield, exile the top card of your library. Until end of turn, you may play that card.
{2}{R}, Sacrifice Experimental Synthesizer: Create a 2/2 white Samurai creature token with vigilance. Activate only as a sorcery.

Myr Retriever

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

Voltage Surge

As an additional cost to cast this spell, you may sacrifice an artifact.
Voltage Surge deals 2 damage to target creature or planeswalker. If this spell's additional cost was paid, Voltage Surge deals 4 damage instead.

Scrapyard Steelbreaker

{1}, Sacrifice another artifact: Scrapyard Steelbreaker gets +2/+1 until end of turn.

Myr Servitor

At the beginning of your upkeep, if Myr Servitor is on the battlefield, each player returns all cards named Myr Servitor from their graveyard to the battlefield.

Reckless Fireweaver

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

Barbed Batterfist

For Mirrodin! (When this Equipment enters, create a 2/2 red Rebel creature token, then attach this to it.)
Equipped creature gets +1/-1.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Mountain

Ingenious Artillerist

Whenever one or more artifacts you control enter, Ingenious Artillerist deals that much damage to each opponent.

Lembas

When Lembas enters, scry 1, then draw a card.
{2}, {T}, Sacrifice Lembas: You gain 3 life.
When Lembas is put into a graveyard from the battlefield, its owner shuffles it into their library.

Ichor Wellspring

When Ichor Wellspring enters or is put into a graveyard from the battlefield, draw a card.