Urza's Builder

When Urza's Builder enters the battlefield, reveal the top five cards of your library. Choose
an artifact land card or Urza's land card from among them and put it into your hand. Put the rest on bottom of your library in any order.
Urza's voice - Whenever an Urza's land enters the battlefield, put a +1/+1 counter on each Assembly-Worker creature you control.
Perfect parts - perfect structures.