Obelisk of Urd

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
As Obelisk of Urd enters the battlefield, choose a creature type.
Creatures you control of the chosen type get +2/+2.

Drill-Skimmer

Flying
Drill-Skimmer has shroud as long as you control another artifact creature. (It can't be the target of spells or abilities.)

Ornithopter of Paradise

Thopter Assembly

Flying
At the beginning of your upkeep, if you control no Thopters other than Thopter Assembly, return Thopter Assembly to its owner's hand and create five 1/1 colorless Thopter artifact creature tokens with flying.

Snare Thopter

Foundry Inspector

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

Flowstone Thopter

{1}: Flowstone Thopter gets +1/-1 and gains flying until end of turn.

Retrofitter Foundry

{3}: Untap Retrofitter Foundry.
{2}, {T}: Create a 1/1 colorless Servo artifact creature token.
{1}, {T}, Sacrifice a Servo: Create a 1/1 colorless Thopter artifact creature token with flying.
{T}, Sacrifice a Thopter: Create a 4/4 colorless Construct artifact creature token.

Chief of the Foundry

Other artifact creatures you control get +1/+1.

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, Urza's Battlethopter's power, put a +1/+1 counter on Liberator.

Filigree Crawler

When Filigree Crawler dies, create a 1/1 colorless Thopter artifact creature token with flying.

Pilgrim's Eye

Flying
When Pilgrim's Eye enters the battlefield, you may search your library for a basic land card, reveal it, put it into your hand, then shuffle.

Whirlermaker

{4}, {T}: Create a 1/1 colorless Thopter artifact creature token with flying.

Adaptive Automaton

As Adaptive Automaton enters the battlefield, choose a creature type.
Adaptive Automaton is the chosen type in addition to its other types.
Other creatures you control of the chosen type get +1/+1.

Hope of Ghirapur

Flying
Sacrifice Hope of Ghirapur: Until your next turn, target player who was dealt combat damage by Hope of Ghirapur this turn can't cast noncreature spells.

Telethopter

Tap an untapped creature you control: Telethopter gains flying until end of turn.

Reconstructed Thopter

Flying
Unearth {2} ({2}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

Thopter Squadron

Flying
Thopter Squadron enters the battlefield with three +1/+1 counters on it.
{1}, Remove a +1/+1 counter from Thopter Squadron: Create a 1/1 colorless Thopter artifact creature token with flying. Activate only as a sorcery.
{1}, Sacrifice another Thopter: Put a +1/+1 counter on Thopter Squadron. Activate only as a sorcery.

Vanquisher's Banner

As Vanquisher's Banner enters the battlefield, choose a creature type.
Creatures you control of the chosen type get +1/+1.
Whenever you cast a creature spell of the chosen type, draw a card.

Skyscanner

Flying
When Skyscanner enters the battlefield, draw a card.

Hangarback Walker

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

Roterothopter

Flying
{2}: Roterothopter gets +1/+0 until end of turn. Activate no more than twice each turn.

Cloud Key

As Cloud Key enters the battlefield, choose artifact, creature, enchantment, instant, or sorcery.
Spells you cast of the chosen type cost {1} less to cast.

Urza's Incubator

As Urza's Incubator enters the battlefield, choose a creature type.
Creature spells of the chosen type cost {2} less to cast.

Herald's Horn

As Herald's Horn enters the battlefield, choose a creature type.
Creature spells you cast of the chosen type cost {1} less to cast.
At the beginning of your upkeep, look at the top card of your library. If it's a creature card of the chosen type, you may reveal it and put it into your hand.

Foundry of the Consuls

{T}: Add {C}.
{5}, {T}, Sacrifice Foundry of the Consuls: Create two 1/1 colorless Thopter artifact creature tokens with flying.

Ornithopter

Door of Destinies

As Door of Destinies enters the battlefield, choose a creature type.
Whenever you cast a spell of the chosen type, put a charge counter on Door of Destinies.
Creatures you control of the chosen type get +1/+1 for each charge counter on Door of Destinies.