Liberator, Urza's Battlethopter

Flash
Flying
You may cast colorless spells and artifact spells as though they had flash.
Whenever you cast a spell, if the amount of mana spent to cast that spell is greater than Liberator's power, put a +1/+1 counter on Liberator.

Arcbound Ravager

Sacrifice an artifact: Put a +1/+1 counter on this 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.)

Mirrorworks

Whenever another nontoken artifact you control enters, you may pay {2}. If you do, create a token that's a copy of that artifact.

Greasefang, Okiba Boss

At the beginning of combat on your turn, return target Vehicle card from your graveyard to the battlefield. It gains haste. Return it to its owner's hand at the beginning of your next end step.

Foundry Inspector

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

Krark-Clan Ironworks

Ichor Wellspring

When this artifact enters or is put into a graveyard from the battlefield, draw a card.

Dross Scorpion

Whenever this creature or another artifact creature dies, you may untap target artifact.

Night Scythe

Flying
Invasion Beams — When this Vehicle enters, create a 2/2 black Necron Warrior artifact creature token.
Crew 2 (Tap any number of creatures you control with total power 2 or more: This Vehicle becomes an artifact creature until end of turn.)

Scrap Trawler

Whenever this creature dies or another artifact you control is put into a graveyard from the battlefield, return to your hand target artifact card in your graveyard with lesser mana value.

Myr Retriever

When this creature dies, return another target artifact card from your graveyard to your hand.