ISIS attack Free Syrian Army and other militant forces in Aykadah, Kafr Shush and Hawar Killis.
It helps if you look at the maps first on the South Front site as you can see some before and afters. Essentially the ISIS units attack into the FSA area where the objective markers are. The other parts are left as they are. By taking those objectives they cut the FSA off from their allied units to the West. So in total the FSA should be cut in two and the Northern elements surrounded with their backs to Turkey.
The article states that ISIS took Hawar Killis but that the FSA retook it.
Interestingly this is up against the Turkish border. I wonder if that has any significance? Maybe for tradinf oil with Turkey?
Another interesting point is that it appears that the FSA and ISIS might have had a truce but that the FSA broke it and so ISIS attacked them back.
But more interestingly is the fact that its ISIS fighting the FSA as they have in the past fought together, for example, in the Raqqa game. This is also outside of the main or usual belligerants in that its not ISIS againt te Syrian army, and so there might not implicitly be much air support. The Syrians want the FSA out as much as ISIS.