Jhoira, Ageless Innovator

{T}: Put two ingenuity counters on Jhoira, then you may put an artifact card with mana value X or less from your hand onto the battlefield, where X is the number of ingenuity counters on Jhoira.

Kelpie Guide

{T}: Untap another target permanent you control.
{T}: Tap target permanent. Activate only if you control eight or more lands.

Shimmer Myr

Flash
You may cast artifact spells as though they had flash.

Steel Hellkite

Flying
{2}: This creature gets +1/+0 until end of turn.
{X}: Destroy each nonland permanent with mana value X whose controller was dealt combat damage by this creature this turn. Activate only once each turn.

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.

Ioreth of the Healing House

{T}: Untap another target permanent.
{T}: Untap two other target legendary creatures.

Enthusiastic Mechanaut

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

Metalwork Colossus

This spell costs {X} less to cast, where X is the total mana value of noncreature artifacts you control.
Sacrifice two artifacts: Return this card from your graveyard to your hand.

Jhoira's Familiar

Flying
Historic spells you cast cost {1} less to cast. (Artifacts, legendaries, and Sagas are historic.)

Myr Battlesphere

When this creature enters, create four 1/1 colorless Myr artifact creature tokens.
Whenever this creature attacks, you may tap X untapped Myr you control. If you do, this creature gets +X/+0 until end of turn and deals X damage to the player or planeswalker it's attacking.

Foundry Inspector

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

Corridor Monitor

When this creature enters, untap target artifact or creature you control.

Meteor Golem

When this creature enters, destroy target nonland permanent an opponent controls.