When this creature enters the battlefield, create that many tokens that are copies of it.) Menace (This creature can't be blocked except by two or more creatures.) Once you announce that you're casting Ruthless Radrat, no player may take actions until you're done casting it
The one thing that bugged me, though, was that "enters the battlefield" effects didn't trigger when you phased back in
"I will Giant Growth my Phyrexian Hydra, and Soul's FI-YA!" #3 - Goblin Grenade Before Fling, there was Goblin Grenade
Creating an online randomizer that lets Urza make his own choices about the spells he casts is a clever way of capturing this (if a little awkward in paper Magic for folks who, like myself, have been reluctant to join the smart phone generation)
If we look closely, we can see that all of the cards are marked