A hero stack of mine was attacked in a game by 3 different stacks during my opponents turn. When my next turn started I saw I had jumped enough experience to get a +1 command bonus.
Looking back through the battle logs, the last 2 stacks that attacked me would have been *after* my hero had accumulated enough experience to level up and get his command bonus. But when I looked at the battle rolls it was clear I wasn't getting the extra +1 command bonus.
If attacking heroes are going to be allowed to level up during a turn then defending heroes should be allowed to level up as well. Otherwise it's not fair to defending heroes that are attacked multiple times.
KGB