Urza's Mine

{T}: Add {C}. If you control an Urza's Power-Plant and an Urza's Tower, add {C}{C} instead.

Urza's Tower

{T}: Add {C}. If you control an Urza's Mine and an Urza's Power-Plant, add {C}{C}{C} instead.

Myr Enforcer

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

Urza's Saga

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Urza's Saga gains "{T}: Add {C}."
II — Urza's Saga gains "{2}, {T}: Create a 0/0 colorless Construct artifact creature token with 'This creature gets +1/+1 for each artifact you control.'"
III — Search your library for an artifact card with mana cost {0} or {1}, put it onto the battlefield, then shuffle.

Frogmite

Mass Hysteria

Springleaf Drum

{T}, Tap an untapped creature you control: Add one mana of any color.

Ancient Stone Idol

Flash
This spell costs {1} less to cast for each attacking creature.
Trample
When Ancient Stone Idol dies, create a 6/12 colorless Construct artifact creature token with trample.

Ornithopter

Expedition Map

{2}, {T}, Sacrifice this artifact: Search your library for a land card, reveal it, put it into your hand, then shuffle.

Great Furnace

Memnite

Galvanic Blast

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

Urza's Power Plant

{T}: Add {C}. If you control an Urza's Mine and an Urza's Tower, add {C}{C} instead.