"It" being the web of consultancy contracts he nurtures through his Tony Blair Associates which have made him a millionaire many times over since he left politics.
He also remains in denial about his role in the destruction of Iraq. Tony was the highest profile international leader to back up W in the 2003 invasion of Iraq. According to Tony, there is no connection whatsoever between the non-stop death spiral that country has been in since then, and that invasion. Blair's backing was by far the single most important bit of foreign support that allowed Bush to pass off the invasion as some sort of international joint action, instead of just another adventure in American imperialism.
Yes, Bush could have and perhaps would have done it without him, but Blair's contribution to the devastation of Iraq, the loss of hundreds of thousands of lives, the displacement of millions, remains his legacy.
And if the ICC were ever to consider establishing some credibility by broadening its mandate beyond black African war criminals, Tony Blair would be a good place to start.