Sai, Master Thopterist

Whenever you cast an artifact spell, create a 1/1 colorless Thopter artifact creature token with flying.
{1}{U}, Sacrifice two artifacts: Draw a card.

Ingenious Prodigy

Skulk (This creature can't be blocked by creatures with greater power.)
This creature enters with X +1/+1 counters on it.
At the beginning of your upkeep, if this creature has one or more +1/+1 counters on it, you may remove a +1/+1 counter from it. If you do, draw a card.

Mm'menon, Uthros Exile

Flying
Whenever an artifact you control enters, put a +1/+1 counter on target creature.

Axgard Artisan

Whenever one or more +1/+1 counters are put on this creature for the first time each turn, create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

Etherium Sculptor

Artifact spells you cast cost {1} less to cast.

Runaway Steam-Kin

Whenever you cast a red spell, if this creature has fewer than three +1/+1 counters on it, put a +1/+1 counter on this creature.
Remove three +1/+1 counters from this creature: Add {R}{R}{R}.

Ion Storm

{1}{R}, Remove a +1/+1 counter or a charge counter from a permanent you control: This enchantment deals 2 damage to any target.

Enthusiastic Mechanaut

Flying
Artifact spells you cast cost {1} less to cast.

Hangarback Walker

This creature enters with X +1/+1 counters on it.
When this creature dies, create a 1/1 colorless Thopter artifact creature token with flying for each +1/+1 counter on this creature.
{1}, {T}: Put a +1/+1 counter on this creature.

Benthic Biomancer

{1}{U}: 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, draw a card, then discard a card.

Thought Monitor

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Flying
When this creature enters, draw two cards.

Cryogen Relic

When this artifact enters or leaves the battlefield, draw a card.
{1}{U}, Sacrifice this artifact: Put a stun counter on up to one target tapped creature. (If a permanent with a stun counter would become untapped, remove one from it instead.)

Tetravus

Flying
This creature enters with three +1/+1 counters on it.
At the beginning of your upkeep, you may remove any number of +1/+1 counters from this creature. If you do, create that many 1/1 colorless Tetravite artifact creature tokens. They each have flying and "This token can't be enchanted."
At the beginning of your upkeep, you may exile any number of tokens created with this creature. If you do, put that many +1/+1 counters on this creature.

Threefold Thunderhulk

This creature enters with three +1/+1 counters on it.
Whenever this creature enters or attacks, create a number of 1/1 colorless Gnome artifact creature tokens equal to its power.
{2}, Sacrifice another artifact: Put a +1/+1 counter on this creature.

Thoughtcast

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

Jetfire, Air Guardian

Living metal (During your turn, this Vehicle is also a creature.)
Flying
{U}{U}{U}: Convert Jetfire, then adapt 3. (If it has no +1/+1 counters on it, put three +1/+1 counters on it.)

Jetfire, Ingenious Scientist

More Than Meets the Eye {3}{U} (You may cast this card converted for {3}{U}.)
Flying
Remove one or more +1/+1 counters from among artifacts you control: Target player adds that much {C}. This mana can't be spent to cast nonartifact spells. Convert Jetfire.

Jetfire, Ingenious Scientist // Jetfire, Air Guardian

The Lord Master of Hell

Starfall — Whenever The Lord Master of Hell attacks, it deals X damage to each opponent, where X is the number of noncreature, nonland cards in your graveyard.

The Emperor of Palamecia

{T}: Add {U} or {R}. Spend this mana only to cast a noncreature spell.
Whenever you cast a noncreature spell, if at least four mana was spent to cast it, put a +1/+1 counter on The Emperor of Palamecia. Then if it has three or more +1/+1 counters on it, transform it.

The Emperor of Palamecia // The Lord Master of Hell

Kappa Cannoneer

Improvise (Your artifacts can help cast this spell. Each artifact you tap after you're done activating mana abilities pays for {1}.)
Ward {4}
Whenever this creature or another artifact you control enters, put a +1/+1 counter on this creature and it can't be blocked this turn.

Falkenrath Exterminator

Whenever this creature deals combat damage to a player, put a +1/+1 counter on it.
{2}{R}: This creature deals damage to target creature equal to the number of +1/+1 counters on this creature.

Marketback Walker

This creature enters with X +1/+1 counters on it.
{4}: Put a +1/+1 counter on this creature.
When this creature dies, draw a card for each +1/+1 counter on it.

Pentavus

This creature enters with five +1/+1 counters on it.
{1}, Remove a +1/+1 counter from this creature: Create a 1/1 colorless Pentavite artifact creature token with flying.
{1}, Sacrifice a Pentavite: Put a +1/+1 counter on this creature.