Alibou, Ancient Witness

Other artifact creatures you control have haste.
Whenever one or more artifact creatures you control attack, Alibou, Ancient Witness deals X damage to any target and you scry X, where X is the number of tapped artifacts you control.

Ultra Magnus, Armored Carrier

Living metal (As long as it's your turn, this Vehicle is also a creature.)
Haste
Formidable — Whenever Ultra Magnus attacks, attacking creatures you control gain indestructible until end of turn. If those creatures have total power 8 or greater, convert Ultra Magnus.

Ultra Magnus, Tactician

More Than Meets the Eye {2}{R}{G}{W} (You may cast this card converted for {2}{R}{G}{W}.)
Ward {2}
Whenever Ultra Magnus attacks, you may put an artifact creature card from your hand onto the battlefield tapped and attacking. If you do, convert Ultra Magnus at end of combat.