It's wise not to disturb an artist at work.

The List

Reclusive Artificer

Haste (This creature can attack and {T} as soon as it comes under your control.)
When this creature enters, you may have it deal damage to target creature equal to the number of artifacts you control.

Duel Decks: Elves vs. Inventors

Haste
When Reclusive Artificer enters the battlefield, you may have it deal damage to target creature equal to the number of artifacts you control.

Magic Origins

Haste (This creature can attack and {T} as soon as it comes under your control.)
When Reclusive Artificer enters the battlefield, you may have it deal damage to target creature equal to the number of artifacts you control.