Donald Trump seems to have no problem making enemies, which is why it's not surprising to see that sometimes-effective hacker collective Anonymous has him in their sights again. Per The Guardian, Anonymous now says that it will "dismantle" Trump's campaign and will "expose what he doesn't want the public to know." It's hard to know what sort of information would actually hurt Trump among his supporters at this point -- he has bragged, after all, that he could shoot people in the middle of 5th Avenue and not lose a single vote -- but Anonymous apparently believes it can dig up the goods.
"We have been watching you for a long time and what we've seen is deeply disturbing. You don't stand for anything but your personal greed and power," said in its declaration. "This is a call to arms. Shut down his websites, research and expose what he doesn't want the public to know. We need you to dismantle his campaign and sabotage his brand."
One thing Anonymous could do that may do damage to Trump's campaign would be to find and leak his tax returns, which is something the candidate who "tells it like it is" has been very reluctant to do. Trump has claimed that he can't release this year's returns because he's being audited but this wouldn't stop him from releasing previous years' returns.
That said, it's equally likely that Anonymous won't do anything major except for vandalizing some of Trump's websites for a day or two. The hacker collective has shown itself to have something akin to attention deficit disorder when it comes to attacking its plethora of targets, although it did help last year with the removal of hundreds of ISIS-affiliated Twitter accounts.