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

As an additional cost to cast this spell, sacrifice an artifact or creature.
Draw two cards.

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

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Draw two cards.

Draw two cards, then sacrifice a permanent.

Whenever an artifact is put into a graveyard from the battlefield, you may gain 5 life.

When Prophetic Prism enters, draw a card.
{1}, {T}: Add one mana of any color.

{1}, {T}, Sacrifice Chromatic Star: Add one mana of any color.
When Chromatic Star is put into a graveyard from the battlefield, draw a card.

Improvise (Your artifacts can help cast this spell. Each artifact you tap after you're done activating mana abilities pays for {1}.)
Menace

Metalcraft — Carapace Forger gets +2/+2 as long as you control three or more artifacts.

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)