With Trump on the way in, all of Obama’s presidential orders are subject to and most likely will be rescinded.
What can he do that will not be immediately countermanded by Trump come January 20th?
Pardons are the big one I can think of.
There’s an active campaign (with both ground and air power being used) against ISIS in Iraq, Syria, and Libya. To a lesser extent small ISIS affiliates in Somalia and Afghanistan have also been under attack in recent months. Those operations are pieces of campaigns that are more focused on the bigger insurgent problem in Afghanistan and dealing with Al-Shabbab in Somalia but are still important pieces of the whole. ISIS is not having a good year. Obama absolutely can continue executing his anti-ISIS plan, while making decisions as the situation develops, to not let them off the ropes.
Maybe gradually touch up all the gray he’s earned the last eight years.
So it looks like most of his legacy will be dismantled.
As far as I know, bin Laden is still dead if that makes you feel any better.
That can be fixed with Photoshop.