I cast Impractical Joke while I had an Aziza, Mage Tower Captain in play. I targeted one of two 3/3 Fractal tokens for the burn spell, and then copied it with Aziza. I wanted to target the second, separate Fractal token but I couldn’t tell from the UI which Fractal my first spell had targeted. I had to guess which Fractal to target with my copied spell. I ended up targeting the same, initial Fractal because I couldn’t tell which one was not already targeted. This was the difference between me delivering lethal damage or not, and I then lost the game a few turns later. Very frustrating! A better UI would make it easy for the player to see which spells on the stack have targeted which creatures.