It really does mean “all creatures”, including your opponent’s.
04-10-2004
wotc
The ability gives +2/+2 to all creatures which are not artifact creatures, as long as every one of those creatures is of the same color. They can have additional colors beyond the one they share, but they all have to share one color. If any creature is not of the shared color, the bonus is lost.
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.