Gonti's Aether Heart

Barricade Breaker

Artifact Creature — Juggernaut (7/5)

Improvise (Your artifacts can help cast this spell. Each artifact you tap after you're done activating mana abilities pays for .)
Barricade Breaker attacks each combat if able.

Foundry Assembler

Artifact Creature — Assembly-Worker (3/3)

Improvise (Your artifacts can help cast this spell. Each artifact you tap after you're done activating mana abilities pays for .)

Paradox Engine

Legendary Artifact

Whenever you cast a spell, untap all nonland permanents you control.

Reservoir Walker

Artifact Creature — Construct (3/3)

When Reservoir Walker enters the battlefield, you gain 3 life and get (three energy counters).

Planar Bridge

Legendary Artifact

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

Prizefighter Construct

Artifact Creature — Construct (6/2)

Aethersphere Harvester

Artifact — Vehicle

Flying
When Aethersphere Harvester enters the battlefield, you get (two energy counters).
Pay : Aethersphere Harvester gains lifelink until end of turn.
Crew 1 (Tap any number of creatures you control with total power 1 or more: This Vehicle becomes an artifact creature until end of turn.)

Scrap Trawler

Artifact Creature — Construct (3/2)

Whenever Scrap Trawler 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.

Mobile Garrison

Artifact — Vehicle

Whenever Mobile Garrison attacks, untap another target artifact or creature you control.
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.)

Consulate Turret

Artifact

: You get (an energy counter).
, Pay : Consulate Turret deals 2 damage to target player or planeswalker.

Inspiring Statuary

Artifact

Nonartifact spells you cast have improvise. (Your artifacts can help cast those spells. Each artifact you tap after you're done activating mana abilities pays for .)

Cogwork Assembler

Artifact Creature — Assembly-Worker (2/3)

: Create a token that's a copy of target artifact. That token gains haste. Exile it at the beginning of the next end step.

Crackdown Construct

Artifact Creature — Construct (2/2)

Whenever you activate an ability of an artifact or creature that isn't a mana ability, Crackdown Construct gets +1/+1 until end of turn.

Heart of Kiran

Legendary Artifact — Vehicle

Flying, vigilance
Crew 3 (Tap any number of creatures you control with total power 3 or more: This Vehicle becomes an artifact creature until end of turn.)
You may remove a loyalty counter from a planeswalker you control rather than pay Heart of Kiran's crew cost.

Lifecrafter's Bestiary

Artifact

At the beginning of your upkeep, scry 1.
Whenever you cast a creature spell, you may pay . If you do, draw a card.

Peacewalker Colossus

Artifact — Vehicle

: Another target Vehicle you control becomes an artifact creature until end of turn.
Crew 4 (Tap any number of creatures you control with total power 4 or more: This Vehicle becomes an artifact creature until end of turn.)

Untethered Express

Artifact — Vehicle

Trample
Whenever Untethered Express attacks, put a +1/+1 counter on it.
Crew 1 (Tap any number of creatures you control with total power 1 or more: This Vehicle becomes an artifact creature until end of turn.)

Aegis Automaton

Artifact Creature — Construct (0/3)

: Return another target creature you control to its owner's hand.

Merchant's Dockhand

Artifact Creature — Construct (1/2)

, , Tap X untapped artifacts you control: Look at the top X cards of your library. Put one of them into your hand and the rest on the bottom of your library in any order.

Metallic Mimic

Artifact Creature — Shapeshifter (2/1)

As Metallic Mimic enters the battlefield, choose a creature type.
Metallic Mimic is the chosen type in addition to its other types.
Each other creature you control of the chosen type enters the battlefield with an additional +1/+1 counter on it.