Rulings

• 2011-01-01
  Since Grand Architect’s last ability doesn’t have a tap symbol in its cost, you can tap a blue creature (including Grand Architect itself) that hasn’t been under your control since your most recent turn began to pay the cost.
• 2011-01-01
  Turning an artifact creature blue with the second ability will override any other color(s) the creature previously had. It will still be an artifact. You may target a blue artifact creature with this ability.
• 2011-01-01
  Other blue creatures you control will get +1/+1 whether they are artifacts or not.
• 2020-08-07
  Because damage remains marked on a creature until the damage is removed as the turn ends, nonlethal damage dealt to a blue creature you control may become lethal if Grand Architect leaves the battlefield during that turn.
• 2020-08-07
  Grand Architect's second ability causes the affected artifact creature to lose any other colors it has, but it doesn't cause it to stop being an artifact.
• 2020-08-07
  You can tap any untapped blue creature you control, including one you haven't controlled continuously since the beginning of your most recent turn, to pay the cost of Grand Architect's mana ability. This includes Grand Architect itself.