Ancient Lumberknot's ability doesn't actually change any creature's power. It changes only the amount of combat damage the creature assigns. All other rules and effects that check power or toughness use the real values, even if they cause damage “equal to a creature's power” to be dealt.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.