Justice League of America, Vol. 1

As Rex delights in killing in the arena the men who have betrayed him, Reena surrenders herself to him in the hopes of having his JLA prisoners released.

Aboard the satellite, the League watch on and listen along with Reena, revealing it is Zatanna who has taken the cat-woman's place.

The League launch an assault upon Repli-Tech's headquarters and capture the doctor responsible for the genetic manipulations who gives up the location of Rex's hideout on an island in the North Atlantic. Attacking it, several of the League are captured and face death in the arena before managing to escape and defeating the hybrids, only to watch them change into a totally animalistic form, leaving behind their humanity. While the same may have happened to Reena and Rex, they disappear in their new forms.