Scrapyard Mongrel 
Creature — Dog
As long as you control an artifact, this creature gets +2/+0 and has trample. (It can deal excess combat damage to the player or planeswalker it's attacking.)
Legality
standardNOT LEGALpioneerLEGALmodernLEGALlegacyLEGALvintageLEGALcommanderLEGAL