Steel Overseer

{T}: Put a +1/+1 counter on each artifact creature you control.

Forest

Corridor Monitor

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

Chamber Sentry

Chamber Sentry enters with a +1/+1 counter on it for each color of mana spent to cast it.
{X}, {T}, Remove X +1/+1 counters from Chamber Sentry: It deals X damage to any target.
{W}{U}{B}{R}{G}: Return Chamber Sentry from your graveyard to your hand.

Shambling Suit

Shambling Suit's power is equal to the number of artifacts and/or enchantments you control.

Stonecoil Serpent

Reach, trample, protection from multicolored
Stonecoil Serpent enters with X +1/+1 counters on it.

Gingerbrute

Haste (This creature can attack and {T} as soon as it comes under your control.)
{1}: Gingerbrute can't be blocked this turn except by creatures with haste.
{2}, {T}, Sacrifice Gingerbrute: You gain 3 life.

Island

Mystic Forge

You may look at the top card of your library any time.
You may cast artifact spells and colorless spells from the top of your library.
{T}, Pay 1 life: Exile the top card of your library.

Breeding Pool

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

Emry, Lurker of the Loch

This spell costs {1} less to cast for each artifact you control.
When Emry, Lurker of the Loch 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.)

Once Upon a Time

If this spell is the first spell you've cast this game, you may cast it without paying its mana cost.
Look at the top five cards of your library. You may reveal a creature or land card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

Manifold Key

{1}, {T}: Untap another target artifact.
{3}, {T}: Target creature can't be blocked this turn.