Panharmonicon

If an artifact or creature entering the battlefield causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Reckless Fireweaver

Whenever an artifact enters the battlefield under your control, Reckless Fireweaver deals 1 damage to each opponent.

Forest

Jolene, the Plunder Queen

Whenever a player attacks one or more of your opponents, that attacking player creates a Treasure token.
If you would create one or more Treasure tokens, instead create those tokens plus an additional Treasure token.
Sacrifice five Treasures: Put five +1/+1 counters on Jolene.

Crackle with Power

Crackle with Power deals five times X damage to each of up to X targets.

Professional Face-Breaker

Menace
Whenever one or more creatures you control deal combat damage to a player, create a Treasure token.
Sacrifice a Treasure: Exile the top card of your library. You may play that card this turn.

Hell to Pay

Hell to Pay deals X damage to target creature. Create a number of tapped Treasure tokens equal to the amount of excess damage dealt to that creature this way.

Crime Novelist

Whenever you sacrifice an artifact, put a +1/+1 counter on Crime Novelist and add {R}.

Karn, Living Legacy

+1: Create a tapped Powerstone token. (It's an artifact with "{T}: Add {C}. This mana can't be spent to cast a nonartifact spell.")
−1: Pay any amount of mana. Look at that many cards from the top of your library, then put one of those cards into your hand and the rest on the bottom of your library in a random order.
−7: You get an emblem with "Tap an untapped artifact you control: This emblem deals 1 damage to any target."

Mountain

Roxanne, Starfall Savant

Whenever Roxanne, Starfall Savant enters the battlefield or attacks, create a tapped colorless artifact token named Meteorite with "When Meteorite enters the battlefield, it deals 2 damage to any target" and "{T}: Add one mana of any color."
Whenever you tap an artifact token for mana, add one mana of any type that artifact token produced.