When Montressor says "I drink to your long life." Montressor knows he is about to be murdered by him.
When Montressor shows us his trowel. This is foreshadowing because you don't just go around carrying a trowel. This means something bad could be coming.
Always think twice about what you are doing. You never know what you could get yourself into.
The clown costume is a symbol of Fortunado. He is a complete food for going all the way down into the catacombs when he clearly knows Montressor has a trowel.
"Its walls had been lined with human remains, piled to the vault overhead, in fashion of the great catacombs of Paris." This is very descriptive and basically shows us what the catacombs look like with words.
Montressor was looking for someone to taste his Amontillado. He came upon Fortundao and took him down to the catacombs. He then tied him up with chains and built a wall in front of him so he couldn't get out, he then died.