In case you missed it, there is a hidden bomb in the 2016 Presidential Campaign, and it's what Donald Trump knows about Fox News Director Roger Ailes. We don't know the exact dirt, but New York Magazine reporter Gabe Sherman, who authored the bomb dropping article in New York Magazine, reports on why Fox News has to play nice with The Donald. [emphasis added]:

It was also thanks to some information he had gathered that Trump was able to do something that no other Republican has done before: take on Fox News. An odd bit of coincidence had given him a card to play against Fox founder Roger Ailes. In 2014, I published a biography of Ailes, which upset the famously paranoid executive. Several months before it landed in stores, Ailes fired his longtime PR adviser Brian Lewis, accusing him of being a source. During Lewis’s severance negotiations, Lewis hired Judd Burstein, a powerhouse litigator, and claimed he had “bombs” that would destroy Ailes and Fox News. That’s when Trump got involved.

“When Roger was having problems, he didn’t call 97 people, he called me,” Trump said. Burstein, it turned out, had worked for Trump briefly in the ’90s, and Ailes asked Trump to mediate. Trump ran the negotiations out of his office at Trump Tower. “Roger had lawyers, very expensive lawyers, and they couldn’t do anything. I solved the problem.” Fox paid Lewis millions to go away quietly, and Trump, I’m told, learned everything Lewis had planned to leak. If Ailes ever truly went to war against Trump, Trump would have the arsenal to launch a retaliatory strike.

Chris Hayes discussed this with Sherman on Monday's All In. From the MSNBC transcript:

HAYES: One of the other things in your piece I thought was really
interesting was the relationship with Trump and Roger Ailes of Fox, which
has been one of the more fascinating sort of sub-plots of this campaign
season.

You talk about a sort of acrimonious departure of one of his Ailes`s top
lieutenants, a guy who sort of threatened to spill the beans, and Trump`s
role in that exit. Tell me that story.

SHERMAN: It`s really fascinating.

And this sort of helped me connect the dots to figure out why Trump has
been able to do something that no other Republicans have done, which is to
go up against Fox News with impunity and kind of brazenly challenge Roger
Ailes and Fox News.

And what I learned is that in 2013 when Roger Ailes fired his long time PR
confidante who was privy to darkest, most interesting controversial secrets
of Fox News, Donald Trump played mediator to helped them work out a
severance deal for Roger Ailes`s PR confidante and learned all of the dirt
that he was going to spill that Roger Ailes ended up paying millions of
dollars to keep secret.

So, now Donald Trump goes into this fight knowing that Ailes presumably
knows that he knows things that he doesn`t want public. And really that`s
why although you`ve seen Fox fight back, it has not been a scorched Earth
campaign. Roger Ailes has not turned over Fox News`s air waves to attack
Trump 24/7 the way he`s done against his other political enemies.

HAYES: So, is your supposition, or your implication at least, that the
knowledge, the sort of secret knowledge that Donald Trump has, the dirt he
has on Roger Ailes has acted as a kind of shield throughout this campaign
in terms of the coverage he`s getting from the network.

SHERMAN: You know, that was my – that was basically what emerged from my
reporting.

Now, it`s important to point out Trump himself did not say, you know, I`m
using this against Roger Ailes. He did tell me that he mediated this
private negotiation. I do know from my reporting that the dirt that Roger
– that Brian Lewis had was very damaging and so it just stands to reason
that all these parties know what Trump knows. And that explains why, you
know, he`s been able to get this far with attacking Ailes.