Yo. Since not all of us have been playing since we were six (computers were just extremely heavy typewriters when I was six), and since I can’t find it on here, and since more people will be looking for the answer to this question, here it is:
AoE stands for Area of Effect. This just means heroes whose hit affects more than one enemy. That’s all. Like Grimm, who can hit three enemies at once, or Little John, who hits everyone, or Hawkmoon, who heals. Basically anybody who doesn’t hit only one target.
Rather like the British spelling/pronunciation system, isn’t it? If you don’t know what it is, you’re not worth explaining it to. Well, you are.
Glossary. In need of.