Super-Duper Death Ray

Trample (This spell can deal excess damage to its target's controller.)
Super-Duper Death Ray deals 4 damage to target creature.

Duplication Device

Whenever you crank Duplication Device, 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.

Head Banger

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

Record Store

Whenever you crank Record Store, 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.

Dispatch Dispensary

Whenever you crank Dispatch Dispensary, create a 2/2 black Rogue creature token with menace.

Mountain

Steamflogger Temp

{6}, {T}: Steamflogger Temp assembles a Contraption. (Put the top card of your Contraption deck face up onto one of your sprockets.)

Forest

Joyride Rigger

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

Jamming Device

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

Secret Base

{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a spell that shares a watermark with Secret Base.

Steamfloggery

Roll a six-sided die. Assemble a number of Contraptions equal to the result. (To assemble a Contraption, put the top card of your Contraption deck face up onto one of your sprockets.)

Boomflinger

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

Oaken Power Suit

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

Work a Double

Assemble two Contraptions. (Put the top card of your Contraption deck face up onto one of your sprockets. Then repeat this process.)

Refibrillator

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

Steamflogger Boss

Other Riggers you control get +1/+0 and have haste.
If a Rigger you control would assemble a Contraption, it assembles two Contraptions instead.

Selfie Preservation

Search your library for a basic land card and reveal it. If there's a tree in its art, put it onto the battlefield tapped. Otherwise, put it into your hand. Then shuffle.

Applied Aeronautics

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

Hammerfest Boomtacular

Whenever you cast a spell with a Goblin Explosioneers watermark, Hammerfest Boomtacular deals 2 damage to any target.

Box of Free-Range Goblins

Roll a six-sided die. Create a number of 1/1 red Goblin creature tokens equal to the result.

Stamp of Approval

As Stamp of Approval enters, choose a watermark.
Creatures you control with the chosen watermark get +1/+1.

Buzz Buggy

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

Steamflogger of the Month

When Steamflogger of the Month enters, it assembles a Contraption for each Contraption you control. (To assemble a Contraption, put the top card of your Contraption deck face up onto one of your sprockets.)

Steamflogger Service Rep

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

Genetic Recombinator

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

Top-Secret Tunnel

Whenever you crank Top-Secret Tunnel, target creature can't be blocked this turn.

Quick-Stick Lick Trick

Whenever you crank Quick-Stick Lick Trick, target creature gets +1/+1 and gains lifelink until end of turn.

Inflation Station

Whenever you crank Inflation Station, target creature gets +3/+3 until end of turn.

Wrench-Rigger

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

Three-Headed Goblin

Triple strike (This creature deals first-strike, regular, and last-strike combat damage.)

Just Desserts

Just Desserts deals π damage to target creature. (π is the ratio of a circle's circumference to its diameter. (It's a smidgen more than 3.))

Goblin Haberdasher

Menace (This creature can't be blocked except by two or more creatures.)
Other creatures you control wearing hats in their art have menace.

Gnomeball Machine

Whenever you crank Gnomeball Machine, create two 1/1 colorless Gnome artifact creature tokens.