Barry Allen and Wally West a.k.a. the two The Flash superheroes are going to have a hard time in the DC universe, as the future issues could pit him against an old and classic villain that poses a huge threat not only to him but also the whole DC universe.
Hunter Zolomon, also known as Reverse Flash or Zoom, is definitely back in the continuity for Flash in the DC universe and with a vengeance. Zolomon is out to make things difficult between Barry and Wally. His plan is still not specific, but he appears in the issue titled "Flash Annual" #1 written by Joshua Williamson and drawn by Christian Duce Fernandez.
This issue is set to be the prelude to "Flash War," which is the long-awaited showdown between Barry and Wally, which a lot of fans view as a bid to see who really is the better Flash. Apparently, Zolomon will drive a wedge between the two using Iris West, Barry's wife, basically initiating the events for "Flash War."
"Flash Annual" #1 has also revealed that it was Zolomon who has been sending henchmen after Iris for her killing of Eobard Thawne who is a variation of Reverse Flash from a different timeline. These henchmen, called The Renegades, consist of some of The Flash' lesser villains such as Mirror Monarch, Commander Cold, Heatstroke, Weather Warlock, and Golden Guardian. They seek to apprehend Iris for what she did to Thawne.
Apparently, Zolomon has been ordering The Renegades all along, and he was doing this from the future, specifically the 25th century, a time where neither Barry or Allen might not have even existed anymore. What is worse is that Zolomon, like Thawne, is doing the plan based on what he thinks is perfect for the continuity and growth of Barry or Wally. This means that he thinks that he is right since he is from the future and possibly will know what will happen if he continued the events of "Flash War."
More about the plans of Zolomon will be revealed in "Flash Annual" and "Flash War" every month.
