"Terrain of Terror" is the story featured in issue #64 of Action Man.
Action Man drives his ultra bike on the mountain where Castle X has been located. A "welcoming party" led by Professor Gangrene drops rocks on Action Man, and when they miss, Gangrene has them dig a pit in the road, but Action Man jumps over it and passes under a trip wire intended to take his head off. Gangrene calls Dr X to tell him Action Man is still alive, so Dr X orders him to get him.
Action Man averts a spike trap and a toxic soup dropped by Gangrene and his goons, then he returns and ties them to a tree while he continues towards Castle X.
When Dr X sees that Gangrene is not returning but instead Action Man is tearing towards the castle, he orders to raise the drawbridge. bur Action Man shoots the control panel and the drawbridge remains down, allowing Action Man to enter. Dr X and his underlings run away to the dungeons, but a shot by Action Man cuts the rope holding the prison bars, leaving the villain trapped in his own castle.