Board Thread:Questions and Answers/@comment-202.166.13.85-20140127105809/@comment-24167698-20140129065901

In theory, only once. However, the button resets slightly before 24 hours run out, so you can pull off two legitimate attacks in one day if you really try. Battle list (about two hours after level up) and sealstone battles are different: it's possible to attack for a sealstone repeatedly.

Alas, there are also bad news: if a person knows the structure of Ayakashi's http requests AND your user id, he can attack you as much as he wants until his AS runs out. If he's really pestering you for silver more than 3 times a day even though you did not level up, you can safely report him, he's a cheater.