In the Princes of Darkness story line , Alex helps save the world by using binding tattoos and Eclipso's black diamond to trap Eclipso for killing his cousin Yolanda Montez , the second Wildcat,.
New 52 Origin
In the New 52, Montez's origin is combined with that of Bruce Gordon's, the original host for Eclipso. As revealed in Team 7 #2, Alex Montez is an Arkham research Scientist who attempts to update the Jekyl formula and experiments on test patient John Akara in a top security elevated prison known as "The Float". Akara however, is overcome by Eclipso and Team 7 arrives to stop him. However, it is shown that Montez himself has already become corrupted by Eclipso himself. Eclipso uses the Alex Montez persona to infiltrate Nilaa. He is escorted by Princess Amythyst as a liason to Earth. The persona is quickly given up as eclipse reveals his true form.
Alex Montez first appeared in JSA #26 of September 2001, he was created by writer Geoff Johns with artists Rags Morales and Michael Bair.
Alex originally wanted the power of Eclipso for himself after the entity had killed his cousin. He gathered 1,000 black diamonds and injected them into his body, except one where Eclipso was stored. He channeled the power through special glyph tattoos he had learned. Eclipso was able to break free once one of the glyphs was broken and killed Alex's girlfriend Soseh Mykros , after which Alex killed himself.
Post-Flashpoint, Alex's character is merged with the previous character Bruce Gordon. He resembles Bruce Gordon in appearance and is also now a research scientist, but retains the name Alex Montez as well as the tribal tattoos the previous incarnation used. In Catwoman #16, it is revealed Montez is using "Bruce Gordon" as an alias, and after retrieving the Black Diamond is fully overtaken by Eclipso.
Major Story Arcs
After the Princes of Darkness arc, Alex joins Black Adam's team (along with Atom Smasher, Brainwave Jr., Nemesis II (Soseh Mykros), Northwind and his fellow Feitherians) to help bring peace to Kahndaq.
During the conquest he and Soseh became lovers. When the JSA attacks Kahndaq, Alex and Soseh fight Hourman and Hawkgirl. During the battle Alex attempts to blast Hourman, but he dodges the blast and it hits Soseh: ripping through her body, the blast kills her on the spot. After this Alex finds that his shoulder was wounded during the fight, so his binding tattoos were messed up and became useless. Eclipso takes control of Alex and with his usual line "Vengeance is mine!" makes Alex, who still has some control, jump from the building.
Alex's tattoos grant him full use of Eclipso's powers.