Where does it say that? Purposefully training things may be against the rules, but theres in no way anywhere that says its wrong to use AOE spells to farm. Why else are the AOE there? For the hell of it? It was meant to hit multiple enemies, thats a given fact. And i am sure you dont use that to hit multiple Incredibly Tough enemies and bring their wraith upon you.

Can you quote anywhere in the rules and TOS or anything that states explictly that says AOE farming is wrong or against the rules?