Urza, Lord High Artificer
{2}{U}{U}
Legendary Creature -- Human Artificer
1/4
When ~this~ enters, create a 0/0 colorless Construct artifact creature token with "~this~ gets +1/+1 for each artifact you control."
Tap an untapped artifact you control: Add {U}.
{5}: Shuffle your library, then exile the top card. Until end of turn, you may play that card without paying its mana cost.