Unbounded Potential

Choose one —
• Put a +1/+1 counter on each of up to two target creatures.
• Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
Entwine {3}{W} (Choose both if you pay the entwine cost.)

Rustvale Bridge

This land enters tapped.
Indestructible
{T}: Add {R} or {W}.

Barbed Spike

When this Equipment enters, create a 1/1 colorless Thopter artifact creature token with flying, then attach this Equipment to it.
Equipped creature gets +1/+0.
Equip {2}

Power Depot

This land enters tapped.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast artifact spells or activate abilities of artifacts.
Modular 1

Marble Gargoyle

Flying
{W}: This creature gets +0/+1 until end of turn.

Slag Strider

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
{1}, Sacrifice an artifact: This creature deals 1 damage to any target.

Foundry Helix

As an additional cost to cast this spell, sacrifice a permanent.
Foundry Helix deals 4 damage to any target. If the sacrificed permanent was an artifact, you gain 4 life.

Monoskelion

This creature enters with a +1/+1 counter on it.
{1}, Remove a +1/+1 counter from this creature: It deals 1 damage to any target.

Arcbound Mouser

Lifelink
Modular 1 (This creature enters with a +1/+1 counter on it. When it dies, you may put its +1/+1 counters on target artifact creature.)

Disciple of the Sun

Lifelink
When this creature enters, return target permanent card with mana value 3 or less from your graveyard to your hand.

Arcbound Slasher

Modular 4 (This creature enters with four +1/+1 counters on it. When it dies, you may put its +1/+1 counters on target artifact creature.)
Riot (This creature enters with your choice of an additional +1/+1 counter or haste.)

Steel Dromedary

This creature enters tapped with two +1/+1 counters on it.
This creature doesn't untap during your untap step if it has a +1/+1 counter on it.
At the beginning of combat on your turn, you may move a +1/+1 counter from this creature onto target creature.

Extruder

Echo {4} (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)
Sacrifice an artifact: Put a +1/+1 counter on target creature.

Arcbound Tracker

Menace
Modular 2 (This creature enters with two +1/+1 counters on it. When it dies, you may put its +1/+1 counters on target artifact creature.)
Whenever you cast a spell other than your first spell each turn, put a +1/+1 counter on this creature.

Knighted Myr

{2}{W}: Adapt 1. (If this creature has no +1/+1 counters on it, put a +1/+1 counter on it.)
Whenever one or more +1/+1 counters are put on this creature, it gains double strike until end of turn.

Caprichrome

Flash
Vigilance
Devour artifact 1 (As this creature enters, you may sacrifice any number of artifacts. It enters with that many +1/+1 counters on it.)

Arcbound Whelp

Flying
{R}: This creature gets +1/+0 until end of turn.
Modular 2 (This creature enters with two +1/+1 counters on it. When it dies, you may put its +1/+1 counters on target artifact creature.)

Sojourner's Companion

Affinity for artifacts
Artifact landcycling {2} ({2}, Discard this card: Search your library for an artifact land card, reveal it, put it into your hand, then shuffle.)

Myr Scrapling

Sacrifice this creature: Put a +1/+1 counter on target creature.

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.

Arcbound Javelineer

{T}, Remove X +1/+1 counters from this creature: It deals X damage to target attacking or blocking creature.
Modular 1 (This creature enters with a +1/+1 counter on it. When it dies, you may put its +1/+1 counters on target artifact creature.)

Arcbound Prototype

Modular 2 (This creature enters with two +1/+1 counters on it. When it dies, you may put its +1/+1 counters on target artifact creature.)

Arcbound Shikari

First strike
When this creature enters, put a +1/+1 counter on each other artifact creature you control.
Modular 2 (This creature enters with two +1/+1 counters on it. When it dies, you may put its +1/+1 counters on target artifact creature.)

Blacksmith's Skill

Target permanent gains hexproof and indestructible until end of turn. If it's an artifact creature, it gets +2/+2 until end of turn.