If you attempt to battle someone of a much lower level, a natural disaster occurs. A natural disaster means an automatic defeat for the person attempting to start the battle.

Whenever a disaster is about to occur, either Minerva or the Owl will notify you.

If someone of a low enough level to warrant a disaster attacks the higher level player first, the higher level player may retaliate with no fear of a disaster. They may only attack the same number of times they were attacked, however.