Deimos was a malevolent and power-hungry wizard, who envisioned himself ruling Skartaris; however, he only managed to shake down some kingdoms sporadically.
It wasn't until Metallo and Silver Banshee supplied Deimos with high-tech energy weaponry that he succeeded in vanquishing most of the free people of Skartaris. In return, Deimos only had to give them a gigantic hunk of Kryptonite dubbed "The Great Stone". He gladly obliged, as he had much more to gain from that bargain.
Deimos's army moved in on the citadel keeping the Stone, and fought Warlord's troops, who had recruited members of the Justice League. When Deimos managed to get inside the tabernacle, he was intercepted by Stargirl. He tried to fight her off with his special gauntlets, but her Staff overpowered him. Metallo promptly stepped in to handle Stargirl, until the Warlord engaged Deimos in a sword fight. After a few exchanges of sword swings, Deimos was disarmed by his superior opponent. While defeated, Deimos mocked Warlord's ideology of freedom and peace, and when he had his guard down, Deimos sprang at him. Morgan dodged the blow, however, and Deimos fell off the cliff, apparently to his death.
Deimos was created by Mike Grell and first appeared in First Issue Special #8 (November 1975). Deimos was the high priest of the kingdom of Thera who resorted to the black arts to take over the city. He then moved on to conquer all of Skartaris, but was thwarted by Travis Morgan, a.k.a. Warlord. Deimos was killed and resurrected a couple of times, making him Warlord's most resilient opponent. Through the course of his incarnations, Deimos used all sorts of means to achieve his goals, whether being sorcery, or advanced technology.