Auriok Sunchaser

Metalcraft — As long as you control three or more artifacts, this creature gets +2/+2 and has flying.

Gaelicat

Flying, vigilance
As long as you control two or more artifacts, this creature gets +2/+0.

Boros Elite

Battalion — Whenever this creature and at least two other creatures attack, this creature gets +2/+2 until end of turn.

Ardent Recruit

Metalcraft — This creature gets +2/+2 as long as you control three or more artifacts.

Rally the Peasants

Creatures you control get +2/+0 until end of turn.
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Court Homunculus

This creature gets +1/+1 as long as you control another artifact.

Ancient Den

Cathar Commando

Flash
{1}, Sacrifice this creature: Destroy target artifact or enchantment.

You're Not Alone

Target creature gets +2/+2 until end of turn. If you control three or more creatures, it gets +4/+4 until end of turn instead.

Plains

Order of Leitbur

Protection from black
{W}: This creature gains first strike until end of turn.
{W}{W}: This creature gets +1/+0 until end of turn.

Ramosian Rally

If you control a Plains, you may tap an untapped creature you control rather than pay this spell's mana cost.
Creatures you control get +1/+1 until end of turn.

Prismatic Strands

Prevent all damage that sources of the color of your choice would deal this turn.
Flashback—Tap an untapped white creature you control. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Lens Flare

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Lens Flare deals 5 damage to target attacking or blocking creature.

Triplicate Spirits

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Create three 1/1 white Spirit creature tokens with flying.

Battle Screech

Create two 1/1 white Bird creature tokens with flying.
Flashback—Tap three untapped white creatures you control. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Magitek Infantry

This creature gets +1/+0 as long as you control another artifact.
{2}{W}: Search your library for a card named Magitek Infantry, put it onto the battlefield tapped, then shuffle.

Guardians' Pledge

White creatures you control get +2/+2 until end of turn.

Idyllic Grange

({T}: Add {W}.)
This land enters tapped unless you control three or more other Plains.
When this land enters untapped, put a +1/+1 counter on target creature you control.