Calculation (both mathematical and behavioral) and tactics. Incredible IQ. Unbreakable will/nerves, for the most part. Hacking also, these days. Basically, mega-Einstein super tactician combat soldier with hilariously over-the-top technology.

"I knew you were gonna plan on knowing the plan I was planning and planned to plan over my plan so I made a plan to make you plan my plans so I could plan your plan, and break every small bone in your body in a very specific way to cause a very specific kind of pain that would make you break emotionally and tell me everything you know. I also know Superman is listening to this conversation and that Barry Allen is watching this happen from the past by running super fast, so I made traps for them both a day in advance. But I also know Barry will run even faster and warn his previous self so I made a double-trap that will slow him down so he can't catch up to old Barry. I also knew the guy writing this comment would make a meta joke about me knowing what he's writing about me".