Ingenious Artillerist

Whenever one or more artifacts you control enter, Ingenious Artillerist deals that much damage to each opponent.

Mirkwood Bats

Flying
Whenever you create or sacrifice a token, each opponent loses 1 life.

Marionette Master

Fabricate 3 (When this creature enters, put three +1/+1 counters on it or create three 1/1 colorless Servo artifact creature tokens.)
Whenever an artifact you control is put into a graveyard from the battlefield, target opponent loses life equal to Marionette Master's power.

Mayhem Devil

Whenever a player sacrifices a permanent, Mayhem Devil deals 1 damage to any target.

Jan Jansen, Chaos Crafter

Haste
{T}, Sacrifice an artifact creature: Create two Treasure tokens.
{T}, Sacrifice a noncreature artifact: Create two 1/1 colorless Construct artifact creature tokens.

Vihaan, Goldwaker

Other outlaws you control have vigilance and haste. (Assassins, Mercenaries, Pirates, Rogues, and Warlocks are outlaws.)
At the beginning of combat on your turn, you may have Treasures you control become 3/3 Construct Assassin artifact creatures in addition to their other types until end of turn.

Nadier's Nightblade

Whenever a token you control leaves the battlefield, each opponent loses 1 life and you gain 1 life.

Molten Gatekeeper

Whenever another creature you control enters, Molten Gatekeeper deals 1 damage to each opponent.
Unearth {R} ({R}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

Workshop Assistant

When Workshop Assistant dies, return another target artifact card from your graveyard to your hand.

Reckless Fireweaver

Whenever an artifact you control enters, Reckless Fireweaver deals 1 damage to each opponent.