Karn, Scion of Urza

+1: Reveal the top two cards of your library. An opponent chooses one of them. Put that card into your hand and exile the other with a silver counter on it.
−1: Put a card you own with a silver counter on it from exile into your hand.
−2: Create a 0/0 colorless Construct artifact creature token with "This token gets +1/+1 for each artifact you control."

Counterspell

Spellseeker

When this creature enters, you may search your library for an instant or sorcery card with mana value 2 or less, reveal it, put it into your hand, then shuffle.

Widget Contraption

Whenever you crank this Contraption, it assembles a Contraption. (Put the top card of your Contraption deck face up onto one of your sprockets.)

Kindly Cognician

Spells you cast that refer to artifacts or Contraptions in their rules text cost {1} less to cast.

Sap Sucker

Whenever you crank this Contraption, add {G}. Until end of turn, you don't lose this mana as steps and phases end.

Machine Over Matter

This spell costs {1} less to cast if you control an artifact creature.
Return target nonland permanent to its owner's hand.

Gift Horse

Whenever you crank this Contraption, roll two six-sided dice. Create a number of 1/1 red Goblin creature tokens equal to the difference between those results.

Really Epic Punch

Target creature you control gets +2/+2 if it's a host or has augment. Then it fights target creature you don't control.

Duplication Device

Whenever you crank this Contraption, until end of turn, target creature becomes a copy of any creature on the battlefield, except it's an artifact in addition to its other types.

Robo-

At the beginning of each end step, if an artifact entered the battlefield under your control this turn,
Augment {2} ({2}, Reveal this card from your hand: Combine it with target host. Augment only as a sorcery.)

Hypnotic Swirly Disc

Whenever you crank this Contraption, target player mills X cards, where X is the number of creatures you control.

Emry, Lurker of the Loch

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
When Emry enters, mill four cards.
{T}: Choose target artifact card in your graveyard. You may cast that card this turn. (You still pay its costs. Timing rules still apply.)

Goblin Slingshot

Whenever you crank this Contraption, creatures you control get +2/+0 and gain trample until end of turn.

Record Store

Whenever you crank this Contraption, look at the top X cards of your library, where X is the number of artifacts you control. Put one of those cards into your hand and the rest on the bottom of your library in a random order.

Tanglepool Bridge

This land enters tapped.
Indestructible
{T}: Add {G} or {U}.

Gnomeball Machine

Whenever you crank this Contraption, create two 1/1 colorless Gnome artifact creature tokens.

Clever Combo

Search your library for a host card or a card with augment, reveal it, put it into your hand, then shuffle.

Optical Optimizer

Whenever you crank this Contraption, until end of turn, target creature becomes an artifact in addition to its other types and gains "{T}: Draw a card."

Dictation Quillograph

Whenever you crank this Contraption, until end of turn, target creature gains "Whenever this creature deals combat damage to a player, you may draw a card. If you do, discard a card."

Seat of the Synod

Breeding Pool

({T}: Add {G} or {U}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Chipper Chopper

Flying
When this creature enters, you may sacrifice another artifact. If you do, put two +1/+1 counters on this creature and it assembles a Contraption. (Put the top card of your Contraption deck face up onto one of your sprockets.)

Sundering Fork

Whenever you crank this Contraption, destroy target artifact.

Contraption Cannon

{2}, Sacrifice this artifact: It deals damage to any target equal to the number of Contraptions you control.

Incite Insight

Assemble X Contraptions. (To assemble a Contraption, put the top card of your Contraption deck face up onto one of your sprockets.)

Half-Squirrel, Half-

Whenever a nontoken creature enters,
Augment {G} ({G}, Reveal this card from your hand: Combine it with target host. Augment only as a sorcery.)

Urza's Saga

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — This Saga gains "{T}: Add {C}."
II — This Saga gains "{2}, {T}: Create a 0/0 colorless Construct artifact creature token with 'This token gets +1/+1 for each artifact you control.'"
III — Search your library for an artifact card with mana cost {0} or {1}, put it onto the battlefield, then shuffle.

Inventors' Fair

At the beginning of your upkeep, if you control three or more artifacts, you gain 1 life.
{T}: Add {C}.
{4}, {T}, Sacrifice Inventors' Fair: Search your library for an artifact card, reveal it, put it into your hand, then shuffle. Activate only if you control three or more artifacts.

Override

Counter target spell unless its controller pays {1} for each artifact you control.

Suspicious Nanny

Whenever this creature deals combat damage to a player, it reassembles target Contraption that player controls. (Gain control of it and move it onto one of your sprockets.)

Spellskite

{U/P}: Change a target of target spell or ability to this creature. ({U/P} can be paid with either {U} or 2 life.)

Heroic Intervention

Permanents you control gain hexproof and indestructible until end of turn.

Cogmentor

Flying
{4}: Reassemble target Contraption you control. (Move it onto another one of your sprockets.)

Mandatory Friendship Shackles

Whenever you crank this Contraption, target creature gets -1/-1 until end of turn.

Temporal Machinations

Return target creature to its owner's hand. If you control an artifact, draw a card.

Jamming Device

Whenever you crank this Contraption, creatures target player controls get -1/-1 until end of turn.

Brainstorm

Draw three cards, then put two cards from your hand on top of your library in any order.

Foundry Inspector

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

Very Cryptic Command

Choose two —
• Scry 3.
• Create a 2/2 black Rogue creature token with menace.
• Add or subtract 1 or one from a number or number word on target spell or permanent until end of turn.
• Return all artifacts target player controls to their owner's hand.

Narset's Reversal

Copy target instant or sorcery spell, then return it to its owner's hand. You may choose new targets for the copy.

Tread Mill

Whenever you crank this Contraption, until end of turn, target creature gets +1/+2, gains vigilance, and becomes an artifact in addition to its other types.

Steamflogger Service Rep

Whenever another Goblin you control enters, you may pay {1}. If you do, this creature assembles a Contraption. (Put the top card of your Contraption deck face up onto one of your sprockets.)

Angelic Rocket

Flying
When this creature enters, you may destroy target nonland permanent.

Clock of DOOOOOOOOOOOOM!

{4}, {T}: Move the CRANK! counter to your Contraption deck's next sprocket and crank any number of that sprocket's Contraptions.

Pet Project

Whenever you crank this Contraption, put target creature card from an opponent's graveyard onto the battlefield under your control.

Head Banger

Whenever you crank this Contraption, target creature must be blocked this turn if able.

Quick-Stick Lick Trick

Whenever you crank this Contraption, target creature gets +1/+1 and gains lifelink until end of turn.

Buzz Buggy

Whenever you crank this Contraption, target creature gets +2/+0 and gains trample until end of turn.

Etherium Sculptor

Oaken Power Suit

Whenever you crank this Contraption, target creature gets +X/+X until end of turn, where X is the greatest power among creatures you control.

Arms Depot

Whenever you crank this Contraption, put two +1/+1 counters on target creature.

Tangled Islet

({T}: Add {G} or {U}.)
This land enters tapped.

Mystical Tutor

Search your library for an instant or sorcery card, reveal it, then shuffle and put that card on top.

Talisman of Curiosity

{T}: Add {C}.
{T}: Add {G} or {U}. This artifact deals 1 damage to you.

Neural Network

Whenever you crank this Contraption, gain control of target creature an opponent controls with power less than or equal to the number of creature cards in its controller's graveyard until end of turn. Untap that creature. It gains haste until end of turn.

Durnan of the Yawning Portal

Whenever Durnan attacks, look at the top four cards of your library. You may exile a creature card from among them. Put the rest on the bottom of your library in any order. For as long as that card remains exiled, you may cast it. That spell has undaunted. (It costs {1} less to cast for each opponent.)
Choose a Background (You can have a Background as a second commander.)

Labro Bot

When this creature enters, return target host card or card with augment from your graveyard to your hand.

Genetic Recombinator

Whenever you crank this Contraption, up to two target creatures each get +2/+2 until end of turn.

Refibrillator

Whenever you crank this Contraption, return target creature card from your graveyard to your hand.

Explore

You may play an additional land this turn.
Draw a card.

Dual Doomsuits

Whenever you crank this Contraption, each time a source you control would deal damage this turn, it deals double that damage instead.

Growth Spiral

Draw a card. You may put a land card from your hand onto the battlefield.

Arcane Denial

Counter target spell. Its controller may draw up to two cards at the beginning of the next turn's upkeep.
You draw a card at the beginning of the next turn's upkeep.

Reshape

As an additional cost to cast this spell, sacrifice an artifact.
Search your library for an artifact card with mana value X or less, put it onto the battlefield, then shuffle.

Top-Secret Tunnel

Whenever you crank this Contraption, target creature can't be blocked this turn.

Guest List

Whenever you crank this Contraption, target creature gets -X/-X until end of turn, where X is the number of creature cards in its controller's graveyard.

Boomflinger

Whenever you crank this Contraption, roll two six-sided dice. This Contraption deals damage to target player or planeswalker equal to the difference between those results.

Thopter Spy Network

At the beginning of your upkeep, if you control an artifact, create a 1/1 colorless Thopter artifact creature token with flying.
Whenever one or more artifact creatures you control deal combat damage to a player, draw a card.

Thoughtcast

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

Wild Crocodile

When this creature enters, search your library for a basic land card, reveal it, put it into your hand, then shuffle.

Tree of Tales

Half-Shark, Half-

At the beginning of your upkeep,
Augment {5}{U} ({5}{U}, Reveal this card from your hand: Combine it with target host. Augment only as a sorcery.)

Division Table

Whenever you crank this Contraption, target player loses 2 life.

Applied Aeronautics

Whenever you crank this Contraption, until end of turn, target creature gets +1/+0, gains flying, and becomes an artifact in addition to its other types.

Waylaying Pirates

When this creature enters, if you control an artifact, tap target artifact or creature an opponent controls and put a stun counter on it. (If a permanent with a stun counter would become untapped, remove one from it instead.)

Forest

Rise and Shine

Target noncreature artifact you control becomes a 0/0 artifact creature. Put four +1/+1 counters on each artifact that became a creature this way.
Overload {4}{U}{U} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Planar Incision

Exile target artifact or creature, then return it to the battlefield under its owner's control with a +1/+1 counter on it.

Auto-Key

Whenever you crank this Contraption, until end of turn, target creature becomes an artifact in addition to its other types and gains "{T}: You gain 3 life."

Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Negate

Accessories to Murder

Whenever you crank this Contraption, target creature gets +X/+0 until end of turn, where X is the number of creatures you control.

Cavern of Souls

As this land enters, choose a creature type.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type, and that spell can't be countered.

Three Visits

Search your library for a Forest card, put it onto the battlefield, then shuffle.

Tropical Island

Joyride Rigger

When this creature enters, it assembles a Contraption. (Put the top card of your Contraption deck face up onto one of your sprockets.)

Sol Ring

All Is Dust

Each player sacrifices all permanents they control that are one or more colors.

Dogsnail Engine

Whenever you crank this Contraption, target player gains life equal to the greatest power among creatures you control.

Steam-Powered

{5}:
Augment {4} ({4}, Reveal this card from your hand: Combine it with target host. Augment only as a sorcery.)

Rapid Prototyper

Whenever you crank Rapid Prototyper, create an X/X colorless Construct artifact creature token, where X is the number of artifacts you control.

Turbo-Thwacking Auto-Hammer

Whenever you crank this Contraption, target creature gains double strike until end of turn.

Treasure Chest

{4}, Sacrifice this artifact: Roll a d20.
1 | Trapped! — You lose 3 life.
2—9 | Create five Treasure tokens.
10—19 | You gain 3 life and draw three cards.
20 | Search your library for a card. If it's an artifact card, you may put it onto the battlefield. Otherwise, put that card into your hand. Then shuffle.

Gnome-Made Engine

When this creature enters, create a 1/1 colorless Gnome artifact creature token.

Lackey Recycler

Whenever you crank this Contraption, put target creature card from your graveyard on top of your library.

Deadly Poison Sampler

Whenever you crank this Contraption, until end of turn, target creature gains "Whenever this creature deals combat damage to a player, destroy target creature that player controls."

Faerie Aerie

Whenever you crank this Contraption, create two 1/1 blue Faerie Spy creature tokens with flying, haste, and "Whenever this token deals combat damage to a player, draw a card." Exile them at the beginning of the next end step.

Spell Suck

Counter target spell, then assemble a Contraption. (Put the top card of your Contraption deck face up onto one of your sprockets.)

First Pick

Destroy target artifact or enchantment. Assemble a Contraption. (Put the top card of your Contraption deck face up onto one of your sprockets.)

Whir of Invention

Improvise (Your artifacts can help cast this spell. Each artifact you tap after you're done activating mana abilities pays for {1}.)
Search your library for an artifact card with mana value X or less, put it onto the battlefield, then shuffle.

Hard Hat Area

Whenever you crank this Contraption, roll two six-sided dice. This Contraption assembles a number of Contraptions equal to the difference between those results. (To assemble a Contraption, put the top card of your Contraption deck face up onto one of your sprockets.)

Mana Leak

Counter target spell unless its controller pays {3}.

Insufferable Syphon

Whenever you crank this Contraption, target player discards a card.

Dispatch Dispensary

Whenever you crank this Contraption, create a 2/2 black Rogue creature token with menace.