Karn, Legacy Reforged

Karn, Legacy Reforged's power and toughness are each equal to the greatest mana value among artifacts you control.
At the beginning of your upkeep, add {C} for each artifact you control. This mana can't be spent to cast nonartifact spells. Until end of turn, you don't lose this mana as steps and phases end.

Voltaic Key

Rolling Hamsphere

Rolling Hamsphere gets +1/+1 for each Hamster you control.
Whenever Rolling Hamsphere attacks, create three 1/1 red Hamster creature tokens, then it deals X damage to any target, where X is the number of Hamsters you control.
Crew 3

Tezzeret, Agent of Bolas

+1: Look at the top five cards of your library. You may reveal an artifact card from among them and put it into your hand. Put the rest on the bottom of your library in any order.
−1: Target artifact becomes an artifact creature with base power and toughness 5/5.
−4: Target player loses X life and you gain X life, where X is twice the number of artifacts you control.

Baleful Strix

Flying, deathtouch
When Baleful Strix enters, draw a card.

Corridor Monitor

When Corridor Monitor enters, untap target artifact or creature you control.

Parhelion II

Flying, first strike, vigilance
Whenever Parhelion II attacks, create two 4/4 white Angel creature tokens with flying and vigilance that are attacking.
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.)

Portal to Phyrexia

When Portal to Phyrexia enters, each opponent sacrifices three creatures of their choice.
At the beginning of your upkeep, put target creature card from a graveyard onto the battlefield under your control. It's a Phyrexian in addition to its other types.

Forensic Gadgeteer

Whenever you cast an artifact spell, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
Activated abilities of artifacts you control cost {1} less to activate. This effect can't reduce the mana in that cost to less than one mana.

Clock of Omens

Tap two untapped artifacts you control: Untap target artifact.

Cybermen Squadron

Nonlegendary artifact creatures you control have myriad. (Whenever a creature with myriad attacks, for each opponent other than defending player, you may create a token copy that's tapped and attacking that player or a planeswalker they control. Exile the tokens at end of combat.)

Sydri, Galvanic Genius

{U}: Target noncreature artifact becomes an artifact creature with power and toughness each equal to its mana value until end of turn.
{W}{B}: Target artifact creature gains deathtouch and lifelink until end of turn.

Excalibur, Sword of Eden

This spell costs {X} less to cast, where X is the total mana value of historic permanents you control. (Artifacts, legendaries, and Sagas are historic.)
Equipped creature gets +10/+0 and has vigilance.
Equip legendary creature {2}