Grell brings Travis Morgan and Deimos together in "final" battle in Warlord 4 (Dec/Jan 76/77).
Travis Morgan and his men besiege Thera at the top of this story. It's all nicely medieval, with towers and catapults. Machiste is in the story, but doesn't play a major role. Deimos has Tara at his side, showing her off as bait to lure Morgan to him.
Using his "book of blood" and a magic orb Deimos creates a giant monster to battle Morgan and his army. Morgan figures out the importance of the orb and shatters it with a bullet. Once the creature is gone, Morgan's army is able to defeat Deimos' garrison.
Deimos insists that he will not submit to being a prisoner, and challenges Morgan to a one on one fight. Although Tara is against the idea, Morgan accepts the challenge.
It's not entirely clear why Morgan chooses to have them fight in darkness. It looks cool, but it's not like it gives either an advantage. Despite being the big villain in the series, Deimos gets slain by Morgan at the end of the battle. Don't worry. We will see him again.
Although he could now rule Thera, Morgan decides to accompany Tara back to Shamballah, and along the way explore Skartaris and help people fight for their freedom. The issue closes on a close-up of the "book of blood," which we see is actually a B-100-D technical manual.