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.)

Plains

Barbed Spike

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

Esper Sentinel

Whenever an opponent casts their first noncreature spell each turn, draw a card unless that player pays {X}, where X is Esper Sentinel's power.

Marble Gargoyle

Flying
{W}: Marble Gargoyle gets +0/+1 until end of turn.

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 Knighted Myr, it gains double strike until end of turn.

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.

Myr Scrapling

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

Razor Hippogriff

Flying
When Razor Hippogriff enters, return target artifact card from your graveyard to your hand. You gain life equal to that card's mana value.

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.)

Bottle Golems

Trample
When Bottle Golems dies, you gain life equal to its power.

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.

Thriving Heath

Thriving Heath enters tapped. As it enters, choose a color other than white.
{T}: Add {W} or one mana of the chosen color.

Caprichrome

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

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.)