When attacking undead, if any units return to castle or hit their intended target, the notification makes the window where you select your champion move away from where ever you are trying to select the champion at. So for example: if I am trying to kill an undead rated 660 hp, I will select a champion with 660 hp to kill it. But while I am trying to select the champion, if any units send a notification of returning to castle or hitting their target the window will scroll wildly away from wherever the cursor is, sometimes this makes you select the wrong champion and you cannot call them back once sent.