Montresor invites Fortunato to his cetaceous and tries to get him drunk so he won't realize that they are getting deeper and deeper into the cetaceous. He was hinting out that he gonna kill him like he said maybe we should go back up there when really he means the opposite. Another trick he used was manipulation and appearing to his ego.
The Climax was when Montressor chained up Fortunato to the cement wall and we didn't know what was going to happen next. Like is he going to leave him there or kill or what.
After the chains him up he starts laughing and gain some conscious and wonder what's going on. While Fortunato thinks this is a joke, Montressor really started to build a wall of cement trapping Fortunato into a cement block with no way out. He started screaming that this isn't funny and needs to let him go but he continued. He kept talking about the amontillado wine, he closed the wall and left a torch. He yelled out to Fortunato but no answer. They never found him till centuries after.