The Incredible Hulk #210, April 1977 issue. "And Call the Doctor... Druid!" Written and edited by Len Wein, pencilled by Sal Buscema, colored by Glynnis W., lettered by J. Costanza, inked by Ernie Chan. Cover by Ernie Chan.
Bruce Banner wakes up in an alley (recovering from the previous issue's battle with the Absorbing Man) to find Doctor Druid, who seeks his help. Going to Bruce's apartment, Druid tells the story of the Hellfire Helix, which burst thousands of years ago, with one piece embedding itself into the man known as Bloodstone, and the other being found by a caveman mutant. This mutant still lives today, having taken on the name of the Maha Yogi, who had battled Thor and the X-Men previously. Now, the Yogi intends to conquer the world... or destroy it! Druid says only the Hulk's power can stop the Yogi.
Meanwhile, at Gamma Base, Major Glenn Talbot (who was married to Betty Ross at this time) is leaving on an extended leave of absence in an attempt to solve his marital problems. It's not a great attempt, as he doesn't take Betty with him.
Back at Druid and Bruce, they're driving to "Merlin Industries," which is where the Yogi has headquartered himself. Getting past the guards, their way is blocked by a firey floor, which Druid gets them past. Then, it gets worse, as a knight wielding a laser lance riding a motorcycle attacks (no, really!). Bruce manages to take out the knight by jamming a piece of oak between the spokes of the cycle, but they're not out of the woods yet, as more knights appear, firing at them with heavy weapons. This time, Druid takes a hand, rendering some immobile, and then using telekinesis to take the guns from the knights and hitting them with them.
Now, all this time, Bruce has been trying to remain calm so he doesn't change into the Hulk, but when he's penned into a corner, "Panic siezes the frail physicist as screaming bullets fly around him... his pulse begins to quicken... his heart begins to race... as the fatal gunfire draws closer... closer... closer! Close, but no cigar!" The Hulk lays into the knights taking them out quickly. However, the Maha Yogi has noticed Druid is exersicing some hypnotic influence over the Hulk. Just then, the Hulk and Druid burst into the Yogi's throne room, and the Yogi tries to override Druid's mental control. The battle of wills is too much for the Hulk's feeble brain, and he passes out! But it's even worse for Druid, as the Yogi commands his lackey Mongu to attack!
Note: This issue's letter column leads off with a letter by none other than modern-day Avengers and Astro City creator Kurt Busiek!
My featured ad of this issue is one of the infamous Hostess ads of the 70's, where super-heroes and super-villains from both Marvel and DC have a one-page adventure which is resolved through the use of Hostess products. Here, Spidey feeds a cupcake to the slowest boxing referree in the history of the world!